# A few questions about RAID 5



## mertov (Nov 17, 2012)

1_ If I build raid 5 with 4 2 tb disc, will I have (4-1)x 2 tb = 6 tb space?
2_ Do I have to format the pc to be able to create raid 5 array? Or adding discs from matrix storage manager is enough?
3_ Is this the best way to protect personal movie,tv series archive?
4_ Lets assume I created raid 5 with 3 disc is it easy to add another disc after?
5_ I have 1 ssd, 1 tb, and 2 2tb disc, one of the 2 tb discs is full the other one is empty, Before I create raid 5 do I have to move my all data or only my data on 2 tb discs?
6_ Do I need a raid card for raid 5? 
7_ What is the difference betwen software raid and hardware raid?
System spec.
i5 3570k @4.5
Asrock extreme4


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## Super XP (Nov 17, 2012)

And quote from Yahoo Answers from wiki info. Regarding 4 Drives.


> Raid 5 is much more faster than regular hard driver , and much more reliable , but it reduces the capacity by 38%
> you'll be able to use 62% of total hard driver





> Raid 5 is a Striped set with distributed parity or interleave parity. Distributed parity requires all drives but one to be present to operate; drive failure requires replacement, but the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. The array will have data loss in the event of a second drive failure and is vulnerable until the data that was on the failed drive is rebuilt onto a replacement drive.


http://answers.yahoo.com/question/index?qid=20090102043809AAWicJw

In regards to question 5, yes you need to back up your data on another drive that will not be in the Raid. Everything will be wiped during the RAID 5 setup.


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## repman244 (Nov 17, 2012)

3. RAID is for redundancy not for backups (it helps you if a drive fails but it doesn't save you if you delete data on it).
6. For RAID 5 I would say yes (if you need the best performance). It will operate much faster with a hardware RAID card.

Also note that RAID 5 is good for reading data but is slower for writing (compared to something like RAID 0).


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## mertov (Nov 17, 2012)

repman244 said:


> 3. RAID is for redundancy not for backups (it helps you if a drive fails but it doesn't save you if you delete data on it).
> 6. For RAID 5 I would say yes (if you need the best performance). It will operate much faster with a hardware RAID card.
> 
> Also note that RAID 5 is good for reading data but is slower for writing (compared to something like RAID 0).



I do not need performance since my os installed on ssd so without raid card I would be able to create raid 5 right? Because my mobo supports raid 0,1,5,10


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## repman244 (Nov 17, 2012)

mertov said:


> I do not need performance since my os installed on ssd so without raid card I would be able to create raid 5 right? Because my mobo supports raid 0,1,5,10



Yeah, if the motherboard supports it then it should work.


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## Super XP (Nov 17, 2012)

Use all 4 drives for RAID 5, just be sure you know which is which pending a single drive failure.


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## mertov (Nov 17, 2012)

Super XP said:


> Use all 4 drives for RAID 5, just be sure you know which is which pending a single drive failure.



You mean 4 2 tb disc by saying use all 4 drives don't you? I have never built raid even raid 0 so I have no idea how to do it. The info about raid 5 on the web is so old.


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## Law-II (Nov 17, 2012)

mertov said:


> The info about raid 5 on the web is so old.



Hi

have to assume your asrock mobo is based on a z77 [as this is not mentioned in the OP]; look here for raid instalation guide - http://www.asrock.com/mb/Intel/Z77 Extreme4/?cat=Manual

Note: you will need the CD that came with your mobo for reference

atb (all the best)

Law-II


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## Super XP (Nov 17, 2012)

mertov said:


> You mean 4 2 tb disc by saying use all 4 drives don't you? I have never built raid even raid 0 so I have no idea how to do it. The info about raid 5 on the web is so old.


I've built many RAID 0's and always everything gets wiped on them. The only issue was one drive failed and I lost everything going. But I always backed up my info. So I was OK.


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## Wrigleyvillain (Nov 17, 2012)

RAID 5 is not really a good option for a "high performance" desktop machine. Also, it dedicates one drive to "parity" for a rebuild if one dies so in this case you would have 4TB space. 

And, NO, it is not "the best" way to protect this data. Not even close. *RAID is not a "backup" * it just allows people, usually in enterprises, to get back up and running quicker if a drive dies (as opposed to having to restore everything from tape or whatever). 

In your case I would first get a real backup scheme in place and then maybe run RAID 1 which mirrors an exact copy of one drive to another in real time. RAID 10 stripes a RAID 1 array into RAID 0 (so it's like RAID 1 + 0 and they call it "ten" and uses 4 drives) but the Intel controller does not support reading from all four at once so performance is not where it could be, unfortunately. Or maybe it was writing to all four. At any rate, I was disappointed in the performance and Googled it and learned this.


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## mertov (Nov 17, 2012)

Law-II said:


> Hi
> 
> have to assume your asrock mobo is based on a z77 [as this is not mentioned in the OP]; look here for raid instalation guide - http://www.asrock.com/mb/Intel/Z77 Extreme4/?cat=Manual
> 
> ...



Thank you so much I will follow instructions that you have sent. I didn't now that kind of gudie exist on Asrock website.


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## Filiprino (Nov 17, 2012)

You can do two RAID5. One were you work on and the other one maintains a backup of the first one.


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## mertov (Nov 17, 2012)

Wrigleyvillain said:


> RAID 5 is not really a good option for a "high performance" desktop machine. Also, it dedicates one drive to "parity" for a rebuild if one dies so in this case you would have 4TB space.
> 
> And, NO, it is not "the best" way to protect this data. Not even close. *RAID is not a "backup" * it just allows people, usually in enterprises, to get back up and running quicker if a drive dies (as opposed to having to restore everything from tape or whatever).
> 
> In your case I would first get a real backup scheme in place and then maybe run RAID 1 which mirrors an exact copy of one drive to another in real time. RAID 10 stripes a RAID 1 array into RAID 0 (so it's like RAID 1 + 0 and they call it "ten" and uses 4 drives) but the Intel controller does not support reading from all four at once so performance is not where it could be, unfortunately. Or maybe it was writing to all four. At any rate, I was disappointed in the performance and Googled it and learned this.



I have a 120 gb vertex 3 ssd so I am looking performance for my secondary storage.To be honest I still do not understand how this raid 5 exactly works. Lets say I built raid 5 with 3 2 tb discs and filled them totally in this case I will have 4 tb data and if one drive fails will I be able to get my all data on the failed disc? Or will I able to get my half data on the failed disc.
Last question is did you ever add a disc after building raid 5?


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## Wrigleyvillain (Nov 17, 2012)

Well tbh I messed around with RAID 0 in the past but am just getting into all this now as I have dedicated to my P55 rig to a home server. Am just running my first RAID 5 array for testing essentially as of last week. I have not yet added a drive but am thinking about removing one/simulating a failure to test rebuilds. Frankly, I do not understand exactly how any drive can die and it rebuilds due to my understanding that just one of the three is dedicated to the "parity" data so I guess I need to read more about it. Intel Rapid Storage Technology package documentation and help has more info.



mertov said:


> Thank you so much I will follow instructions that you have sent. I didn't now that kind of gudie exist on Asrock website.



Ya that may be from Intel.


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## Mindweaver (Nov 17, 2012)

I would not setup a software raid 5... I would only setup RAID 0 or 1.. 0 for speed and 1 for redundancy.. You can try RAID 10.. It's RAID 1 and RAID 0 together 1+0... It just costs half your space... 

 If you lose power you have the chance of losing your RAID 5 configuration.. Which sucks, because you could lose everything. I would only recommend RAID 5 with a Hardware RAID card with a battery backup on the card (*BBU*) _Battery Backup Unit_. Plus, using software will kill your CPU performance. I've had Hardware RAID 5 setups with out a BBU to lose the configuration and that sucks ass. Just my two cents.

*EDIT: Using RAID 5 I would use 4 drives and remember adding to many drives to a RAID 5 can hurt performance, but 4 drives have always performed well.  *


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## FordGT90Concept (Nov 17, 2012)

mertov said:


> 1_ If I build raid 5 with 4 2 tb disc, will I have (4-1)x 2 tb = 6 tb space?
> 2_ Do I have to format the pc to be able to create raid 5 array? Or adding discs from matrix storage manager is enough?
> 3_ Is this the best way to protect personal movie,tv series archive?
> 4_ Lets assume I created raid 5 with 3 disc is it easy to add another disc after?
> ...


1. Yes.
2. The disks will have to be formatted when the RAID array is created.  I think it can spare all disks not being added to the RAID array but back up everything just in case a mistake is made.
3. A backup is better (e.g. external drive in a lock box).  RAID5 will only protect the data from a single hard drive failure at a time.
4. No, unless it is a hot-spare where it only takes the place of a defective drive.  Parity information has to be recalculated for all the drives in order to add more to the array.  The controller might be able to do it without formatting--check documentation.
5. Nothing can be on the disks you intend to RAID.  All disks will be wiped when the RAID is created.
6. No, if your motherboard controller supports it.
7. Software is software (often Windows copying data to separate hard drives without the disk controller knowing they are RAIDed), hardware is hardware (software doesn't even know the volume is a RAID withought digging through drivers for it).  If it isn't hardware RAID, it isn't worth doing.


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## repman244 (Nov 17, 2012)

mertov said:


> I still do not understand how this raid 5 exactly works. Lets say I built raid 5 with 3 2 tb discs and filled them totally in this case I will have 4 tb data and if one drive fails will I be able to get my all data on the failed disc? Or will I able to get my half data on the failed disc.



I hope this will help:







If one drive fails you don't loose any data because the data that was on the failed drive is spread on the other drives.
So when you replace the failed drive your RAID 5 array will automatically rebuilt.



> 7_ What is the difference betwen software raid and hardware raid?



With a hardware RAID controller card you have a dedicated CPU on that board for handling the RAID. It's much faster than the software RAID that comes with the motherboard.


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## Disparia (Nov 17, 2012)

Hardware is nice if the situation calls for it, but I agree with Intel that those situations are becoming fewer and fewer:



			
				Sept 2010 said:
			
		

> "I'll plead guilty. We stood up here 10 years ago and told you software RAID sucked, you didn't want it, it wasn't a viable solution," Susan Bobholz of Intel's storage product marketing group told attendees at a Wednesday SAS and RAID session at the Intel Developer Forum in San Francisco.
> 
> "But that's one of those things that's starting to change in the industry," she added. "Software RAID is no longer the evil stepchild of the enterprise anymore."
> 
> ...



To be fair they are talking about 4/8-port controller on Patsburg chipsets (X79, C600), but they're also talking about workstation and server applications. For the consumer, Intel hit their stride starting with the ICH9R in my opinion.

Generation vs generation, AMD chipsets do perform less than their counterparts. My array which did 400MB/s on ICH10R does around 250MB/s on SB950. Since it's just storage, not really noticeable.


As everyone else has said, if you do go ahead with RAID-5 you'll still want to backup anything that can you absolutely can't lose.


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## mertov (Nov 17, 2012)

Mindweaver said:


> I would not setup a software raid 5... I would only setup RAID 0 or 1.. 0 for speed and 1 for redundancy.. You can try RAID 10.. It's RAID 1 and RAID 0 together 1+0... It just costs half your space...
> 
> If you lose power you have the chance of losing your RAID 5 configuration.. Which sucks, because you could lose everything. I would only recommend RAID 5 with a Hardware RAID card with a battery backup on the card (*BBU*) _Battery Backup Unit_. Plus, using software will kill your CPU performance. I've had Hardware RAID 5 setups with out a BBU to lose the configuration and that sucks ass. Just my two cents.
> 
> *EDIT: Using RAID 5 I would use 4 drives and remember adding to many drives to a RAID 5 can hurt performance, but 4 drives have always performed well.  *



Are you sure about loosing everything? Because the city that I live still has power cut problem even though it is capital and I thought raid 5 would give me a chance to recollect my data if anything bad happens. I knew only raid 0 has loosing all data risk.


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## mertov (Nov 17, 2012)

FordGT90Concept said:


> 1. Yes.
> 2. The disks will have to be formatted when the RAID array is created.  I think it can spare all disks not being added to the RAID array but back up everything just in case a mistake is made.
> 3. A backup is better (e.g. external drive in a lock box).  RAID5 will only protect the data from a single hard drive failure at a time.
> 4. No, unless it is a hot-spare where it only takes the place of a defective drive.  Parity information has to be recalculated for all the drives in order to add more to the array.  The controller might be able to do it without formatting--check documentation.
> ...



Thank you so much  Is there any risk loosing all data on raid 5 due to power cut etc?


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## FordGT90Concept (Nov 17, 2012)

That's always a risk.  A UPS is usually a good investment.


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## mertov (Nov 17, 2012)

repman244 said:


> I hope this will help:
> 
> http://blog.everycity.co.uk/wp-content/uploads/2008/10/raid5.png
> 
> ...



I have seen that picture but I still do not understand how I do not loose any data. Lets say 3 same discs on a raid 5 array and the the raid 5 array is totally full. If one drive fails I should be able to get half of the data from the failed disc. If raid 5 had total data security no none would ever built raid 1 in my opinion


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## FordGT90Concept (Nov 17, 2012)

When a drive fails, it uses the parity information on the other drives to rebuild the data on the failed drive.  This process takes hours to complete but, so long as nothing happens to the other drives in the meantime, no data is lost.


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## repman244 (Nov 17, 2012)

mertov said:


> I have seen that picture but I still do not understand how I do not loose any data. Lets say 3 same discs on a raid 5 array and the the raid 5 array is totally full. If one drive fails I should be able to get half of the data from the failed disc. If raid 5 had total data security no none would ever built raid 1 in my opinion



One of the advantages is that RAID 5 allows more space used (RAID 1 is total space split in half) and also allow faster reads (with the same number of disks) but has lower writes.

If you have 4 drives in RAID 5 each drive is split into 3 blocks + parity block (the reason behind loosing some space).
The parity, like FordGT90Concept	 has the information to rebuild the disk...so instead of "backing up" on one drive (like RAID 1), the "backup" is spread across all of the disks.

Hope I got it right


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## Wrigleyvillain (Nov 18, 2012)

The Intel onboard is better than straight-up software RAID like madm in linux or whatever and is usually referred to as "Fake RAID". But no it's nowhere as good as a higher end dedicated controller from, like, LSI.

The most affordable good SATA/SAS RAID controller right now is the IBM M1015 a rebranded LSI that you can get on ebay for $65. But it requires a $100 add-in chip to do RAID 5 (0, 1 and 10 without). Old Dell Perc 5's aren't bad either.

Interestingly enough timing-wise, I decided to switch some ports around and my test RAID 5 array has to rebuild now. For some reason I only see activity on one of the three disks though. Maybe this is different than having to rebuild a new clean one though. Guess that makes sense. Though not sure exactly what it's doing. Yeah it will take like 10 hours too. 1.4TB array.


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## repman244 (Nov 18, 2012)

Another thing that might push people away from hardware RAID controllers is the boot time (I think it's similar for all of them - but not sure) when running on standard consumer boards (does not apply for servers). 
My controller needs around a minute or even more to boot (itself) and after that the Windows start loading. 
I personally don't mind this but to those who want fast boot times, this can be a deal breaker (especially if you run an SSD).


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## Aquinus (Nov 18, 2012)

mertov said:


> 1_ If I build raid 5 with 4 2 tb disc, will I have (4-1)x 2 tb = 6 tb space?


Yes


mertov said:


> 2_ Do I have to format the pc to be able to create raid 5 array? Or adding discs from matrix storage manager is enough?


When you first make the raid you must reformat, but if you add disks to an array when it has already been created you can just resize your partition.


mertov said:


> 3_ Is this the best way to protect personal movie,tv series archive?


Yes, it is a better method of making sure that you don't lose what is important to you. For example, my RAID stores my music, video, pictures, and some software installers.


mertov said:


> 4_ Lets assume I created raid 5 with 3 disc is it easy to add another disc after?


Yes, but it may take time to resize. It may have to re-distribute parity across that disk so it might have to rebuild every time you add a disk.


mertov said:


> 5_ I have 1 ssd, 1 tb, and 2 2tb disc, one of the 2 tb discs is full the other one is empty, Before I create raid 5 do I have to move my all data or only my data on 2 tb discs?


You can, but not if you're going to be using that 2Tb drive in your RAID.





mertov said:


> 6_ Do I need a raid card for raid 5?


No, but hardware RAID is more reliable, faster, and can let you use a BBU to prevent data loss when using a write-back cache.


mertov said:


> 7_ What is the difference betwen software raid and hardware raid?


Performance, really. A RAID controller will do all the RAID/SCSI commands on the controller instead of the processor. All in all, on any modern day computer you won't notice an impact from it using your CPU but when using really fast drives (15k RPM or SSDs,) in RAID it is more noticeable, but I have a RAID-0 of two Force GTs and I still get 900MB-1GB/sec using the X79 PCH. So for your purposes, the PCH FakeRAID controller should be fine.




repman244 said:


> My controller needs around a minute or even more to boot (itself) and after that the Windows start loading.


I've used an LSI controller that initializes in a matter of seconds, are you sure it's not just the Xeon boards you're using? Server or not, any Xeon machine I've used tends to take forever to go through everything in the BIOS for the motherboard.


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## repman244 (Nov 18, 2012)

Aquinus said:


> I've used an LSI controller that initializes in a matter of seconds, are you sure it's not just the Xeon boards you're using? Server or not, any Xeon machine I've used tends to take forever to go through everything in the BIOS for the motherboard.



Sorry, I should of said I was talking about my Adaptec (in my PC). It takes a minute to initialize the kernel (of the controller) which is a known thing for Adaptec. But like I said I don't know about all the brands out there (I don't remember but Areca controllers also take a while).

This doesn't happen only with the 2405 but with an older Adaptec SATA controller as well (the one in my ML350) if used in consumer boards.

The funny thing is, if I put it in one of my server it initializes in less than a second, so I guess they were built for servers (my theory is that it loads it's BIOS into the servers BIOS somehow or something similar).

The boards do take longer to initialize due to many components that are on the board (RAD controllers, disk spin up, ILO etc.) but it's still faster than my PC due to the controller.

EDIT: was the LSI that you used a hardware controller?


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## Aquinus (Nov 18, 2012)

repman244 said:


> EDIT: was the LSI that you used a hardware controller?



3ware Internal 9750-4i SATA/SAS 6Gb/s PCI-Express ...
Yes.


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## repman244 (Nov 18, 2012)

Aquinus said:


> 3ware Internal 9750-4i SATA/SAS 6Gb/s PCI-Express ...
> Yes.



I could try and put my HP P400 into my PC and see if it boots faster (the P400 has a LSI chip).

It could be that Adaptec has a shitty controller BIOS, but I can't complain I got it almost for free.

Did you use your LSI in a PC with UEFI or did it have BIOS, could this be the cause?


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## Aquinus (Nov 18, 2012)

repman244 said:


> Did you use your LSI in a PC with UEFI or did it have BIOS, could this be the cause?



The computers it ran on had a typical BIOS but the LSI controller has a GUI op-rom. It usually does't take more than 10 seconds to initialize (tops.)


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## Wrigleyvillain (Nov 18, 2012)

Aquinus said:


> Yes, it is a better method of making sure that you don't lose what is important to you. For example, my RAID stores my music, video, pictures, and some software installers.



I am sorry but this is just not correct and gives a dangerous wrong impression. As I said earlier, RAID with redundancy/parity is  better than having absolutely with no multiple copies of data at all but itself is *not designed as true backup scheme and should not be treated as one* and if you rely on it as such you are gonna get burned. It's not a "better method" of data protection at all. It's a method to help protect one's ass against HDD failure time-wise plus possibly some performance increases in certain scenarios depending on the RAID level etc.

As always, you need multiple copies of your important data including your OS install on another HDD or tape or optical disc or *something*. You should also take a copy or two of your most important simply-can't-ever-lose stuff and have it "off-site" in a different physical location. A lot of good your four copies on three types of media backups are gonna do you if they are all in your house (or business) and it burns to the ground.


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## Aquinus (Nov 18, 2012)

Wrigleyvillain said:


> I am sorry but this is just not correct and gives a dangerous wrong impression. As I said earlier, RAID with redundancy/parity is better than having absolutely with no multiple copies of data at all but itself is not designed as true backup scheme and should not be treated as one and if you rely on it as such you are gonna get burned. It's not a "better method" of data protection at all. It's a method to help protect one's ass against HDD failure time-wise plus possibly some performance increases in certain scenarios depending on the RAID level etc.
> 
> As always, you need multiple copies of your important data including your OS install on another HDD or tape or optical disc or something. You should also take a copy or two of your most important simply-can't-ever-lose stuff and have it "off-site" in a different physical location. A lot of good your four copies on three types of media backups are gonna do you if they are all in your house (or business) and it burns to the ground.



I never said it was a replacement for a backup, but RAID-5 is a lot more reliable than depending on just a single disk and a backup than a RAID-5 and a backup. I'm not talking about RAID as a backup, but as a fail-safe. If you do forget to backup your stuff RAID-5 can save you.

He was asking about RAID and not options for backup. If you look at my answer there, I didn't mention the word backup at all. Backups aren't always 100% in sync with your RAID because you won't be constantly copying data. You put it on a schedule so there can still be things on your drive or RAID that could have changed between now and then. The point of RAID is to give you a failsafe while minimizing down-time due to hardware failure, not to be a backup. However RAID does give you redundancy so you're less likely to screw yourself if you're running a RAID and a drive fails in case you don't have a back up.

So all in all: Read what I said and don't go assuming that I meant "you don't need a backup" when I said absolutely nothing of the sort. I'm a systems admin, I have a backup of my own RAID, and I manage an off-site backup for work as well as manage backups for all of our servers to be rotated off-site. I think that I know what I'm talking about and I don't appreciate you putting words in my mouth just because I didn't cover back-ups because that isn't what he asked.


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## mertov (Nov 18, 2012)

Aquinus said:


> Yes
> 
> When you first make the raid you must reformat, but if you add disks to an array when it has already been created you can just resize your partition.
> 
> ...



Thank you so much for the answer. My final plan is buying two more 2 tb discs and after creating raid 5 array and never touching it. But, the only raid card that I can afford is this
http://www.hepsiburada.com/liste/di...Details.aspx?productId=bd87025&categoryId=119
Do you think it is useful? And my last question is after creating raid 5 in case I have to format pc can I do it without disjointing raid 5 and loosing data, with raid card or without the raid card?


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## repman244 (Nov 18, 2012)

mertov said:


> Thank you so much for the answer. My final plan is buying two more 2 tb discs and after creating raid 5 array and never touching it. But, the only raid card that I can afford is this
> http://www.hepsiburada.com/liste/di...Details.aspx?productId=bd87025&categoryId=119
> Do you think it is useful? And my last question is after creating raid 5 in case I have to format pc can I do it without disjointing raid 5 and loosing data, with raid card or without the raid card?



Don't bother with that card it's PCI and only SATA I. If Performance isn't an issue just use your on-board RAID.


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## Wrigleyvillain (Nov 18, 2012)

Ok did not mean to seem to jump all over you but my impression from #3 in OP is that he is looking for a way to keep his data safe as well and it's potentially dangerous to say RAID 5 is a "better way" to "protect data" without more specifically pointing out that one needs a real backup as well same as usual.

In other news, my RAID 5 array took 16 hours to rebuild. Yeah not such a great option, IMO, but RAID 1 is boring, lol. Will probably run 10 when I get a real controller (the one I link below).

Yes do not bother with that card it's not going to do any better than your onboard, really and is also "fake RAID" afaik. If you want a real RAID card you can actually afford buy one of these plus a mini-SAS to like 4x SATA "breakout cable". Can get a bracket for $10 also on eBay.

There is also a used Dell Perc 5i for sale for $50 on OCN.


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## mertov (Nov 18, 2012)

repman244 said:


> Don't bother with that card it's PCI and only SATA I. If Performance isn't an issue just use your on-board RAID.



Performance is not an issue at all  I am just asking that raid card because, as it is mentioned above  loosing all data on raid 5 kind of scared me


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## Wrigleyvillain (Nov 18, 2012)

Losing all data anytime should scare you, dude. You have backups now, right?


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## mertov (Nov 18, 2012)

Wrigleyvillain said:


> Ok did not mean to seem to jump all over you but my impression from #3 in OP is that he is looking for a way to keep his data safe as well and it's potentially dangerous to say RAID 5 is a "better way" to "protect data" without more specifically pointing out that one needs a real backup as well same as usual.
> 
> In other news, my RAID 5 array took 16 hours to rebuild. Yeah not such a great option, IMO, but RAID 1 is boring, lol. Will probably run 10 when I get a real controller (the one I link below).
> 
> ...



The problem is I live in Turkey and no shopping site sends anything to Turkey newegg,amazon etc and the only affordable raid card I could find was it. The others are extremely expensive like 1000$


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## mertov (Nov 18, 2012)

Wrigleyvillain said:


> Losing all data anytime should scare you, dude. You have backups now, right?



Yes on my external hard drive. I going to ask a very stupid question now that I should have asked in my first post. Which way is the safer raid 5 or independent drives?


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## repman244 (Nov 18, 2012)

mertov said:


> Which way is the safer raid 5 or independent drives?



In your case it's not quite clear I would say. If you have everything backed up then I would go with independent drives.
RAID 5 is good in case a drives fails but you still need to access to the data all the time (imagine having some critical data there that is read by a program and it's critical for you not to interrupt it). 
A drawback is that you will run it on your board (it's not as reliable as hardware RAID), and in case of some weird error your whole array can be destroyed (I'm also not sure what happens with your RAID array if your motherboard dies and you need a new one...).

A drawback for single drive configuration would be that you can't have all the data "backed up"/ready all the time in case of a drive fail (you probably do weekly or maybe daily backups, no point in doing backups every hour).

This is how I see this, if I'm wrong someone please correct me.


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## Steevo (Nov 18, 2012)

mertov said:


> I have seen that picture but I still do not understand how I do not loose any data. Lets say 3 same discs on a raid 5 array and the the raid 5 array is totally full. If one drive fails I should be able to get half of the data from the failed disc. If raid 5 had total data security no none would ever built raid 1 in my opinion



I think you are asking how the parity works, and how the 38% of data is equal to the rest of the data. Don't think of it as "if I have a picture and each drive holds 25% of the picture" that is reassembled data, hard disks do NOT store data this way. They store the actual binary, plus encoding bits, in a specific data format. 


So in short, the 25% may be gone, but the other three parity sectors contain enough information for a highly accurate rebuild of the data. 

http://www.google.com/url?sa=t&rct=...sg=AFQjCNHvzFTlimDmnnUoxl-Sz5JaJOcmaQ&cad=rja


Lattice and QAM of varying degrees is how we have gotten where we are, and has proven itself very robust and reliable.


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## mertov (Nov 18, 2012)

repman244 said:


> In your case it's not quite clear I would say. If you have everything backed up then I would go with independent drives.
> RAID 5 is good in case a drives fails but you still need to access to the data all the time (imagine having some critical data there that is read by a program and it's critical for you not to interrupt it).
> A drawback is that you will run it on your board (it's not as reliable as hardware RAID), and in case of some weird error your whole array can be destroyed (I'm also not sure what happens with your RAID array if your motherboard dies and you need a new one...).
> 
> ...



That is exactly how I understand this situtation. I think the real question is how often does the weird error occur. Because, I have read a lot of issues about raid 0 destroyed with no reason.


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## Steevo (Nov 18, 2012)

I have ran RAID 0 for years with no issues on mechanical drives.

Weird issues are usually caused by too high of an overclock or the disk bus being overclocked on older drives or boards with locked bus clocks.

That being said, be prepared to lose all of your data. RAID 0 is merely for performance and to maintain the same amount of storage as you paid for. Another way to do it if you aren't looking for the moderate performance boost is to use JBOD.


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## mertov (Nov 18, 2012)

Steevo said:


> I have ran RAID 0 for years with no issues on mechanical drives.
> 
> Weird issues are usually caused by too high of an overclock or the disk bus being overclocked on older drives or boards with locked bus clocks.
> 
> That being said, be prepared to lose all of your data. RAID 0 is merely for performance and to maintain the same amount of storage as you paid for. Another way to do it if you aren't looking for the moderate performance boost is to use JBOD.



I had researched jbod before I researched raid 5. Probably my motherboard does not support jbod because I did not find any info about jbod on asrock websitea and there is less info about jbod than even raid 5


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## Aquinus (Nov 18, 2012)

Wrigleyvillain said:


> In other news, my RAID 5 array took 16 hours to rebuild. Yeah not such a great option, IMO, but RAID 1 is boring, lol. Will probably run 10 when I get a real controller (the one I link below).



Ouch, my X79 takes something like 4-5 hours for 3x1Tb drives and my Phenom II rig with an nForce 750a only takes about 3 hours. 10 only helps write speeds, RAID-5 and RAID-6 read almost as quickly as RAID-0 does on a good controller because you're skipping the parity where when you write you have to calculate and write each parity block. Read speed scales better with the number of disks you add to RAID-5 and RAID-6 as well. You also don't have to add disks in pairs with RAID-5 and RAID-6 as you do in RAID-10. A good example is how you can run 5 drives in RAID-5 and 6 but you need either 4 or 6 for 10. So really, it depends highly on what you're doing to make 10 a better option than 5 or 6 imho. For storage, 5 and 6 is a lot nicer, but if you're using it as your OS drive or you're going to be doing video editing or run a heavily loaded database, 10 is going to be the faster option.



mertov said:


> I had researched jbod before I researched raid 5. Probably my motherboard does not support jbod because I did not find any info about jbod on asrock websitea and there is less info about jbod than even raid 5



RAID-5 is a safe bet. It has saved me many times even though I have a backup drive because there is always that data that hasn't been backed up yet, it's worth it.


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## mertov (Nov 18, 2012)

Aquinus said:


> Ouch, my X79 takes something like 4-5 hours for 3x1Tb drives and my Phenom II rig with an nForce 750a only takes about 3 hours. 10 only helps write speeds, RAID-5 and RAID-6 read almost as quickly as RAID-0 does on a good controller because you're skipping the parity where when you write you have to calculate and write each parity block. Read speed scales better with the number of disks you add to RAID-5 and RAID-6 as well. You also don't have to add disks in pairs with RAID-5 and RAID-6 as you do in RAID-10. A good example is how you can run 5 drives in RAID-5 and 6 but you need either 4 or 6 for 10. So really, it depends highly on what you're doing to make 10 a better option than 5 or 6 imho. For storage, 5 and 6 is a lot nicer, but if you're using it as your OS drive or you're going to be doing video editing or run a heavily loaded database, 10 is going to be the faster option.
> 
> 
> 
> RAID-5 is a safe bet. It has saved me many times even though I have a backup drive because there is always that data that hasn't been backed up yet, it's worth it.



Lets say my computer infected by virus and the only solution is format. Does it mean loosing all data or can I only format os without touching raid 5? Also unplugging and plugging any disc for cleaning inside the case does destroy raid 5?


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## Aquinus (Nov 18, 2012)

mertov said:


> Lets say my computer infected by virus and the only solution is format. Does it mean loosing all data or can I only format os without touching raid 5? Also unplugging and plugging any disc for cleaning inside the case does destroy raid 5?



I would say be careful with viruses anyways because they can cause havoc no matter what your disk configuration is. 

Don't unplug any drives while your machine is running. The computer won't stop running but your RAID will drop to degraded and even after plugging the old drive back in, it will want to rebuild the entire RAID which will take hours (you can still use the system while this occurs though.) Just don't go unplugging anything while the machine is on and you'll be fine. Install a good anti-virus and be smart about using the internet.


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## Steevo (Nov 18, 2012)

If you are worried about infection of the OS simply partition the OS and swap/temp files and another for your personal data. 

Why would you unplug a drive? And to answer your question yes, RAID 5 will allow for continued operation while a drive is missing, or replaced and rebuilt.

I have had to do it once on a Highpoint controller, it took 18 hours to rebuild a 1TB array with three partitions, databases and backups. Performance was degraded by about 50% while the rebuild took place.


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## Aquinus (Nov 18, 2012)

Steevo said:


> I have had to do it once on a Highpoint controller, it took 18 hours to rebuild a 1TB array with three partitions, databases and backups. Performance was degraded by about 50% while the rebuild took place.



You're also stuck up s**ts creak without a paddle if another drive goes while it is rebuilding. So people who are extra paranoid about losing their stuff uses RAID-6. In all honestly, just make sure to have a backup of your RAID and you'll be golden for anything that might happen with the exception of your place of residence being burnt down, or flooded, or some other event that happens to destroy your computer.

All I guess I'm saying is consider what is reasonable for measure you want to take to protect your data. How important is that data to you? For example, pictures of my daughter are priceless, if I lose them I will never get them back. I have them backed up in more places than you can count on one hand, but recent downloads are only on my SSDs or my RAID, they haven't touched my backup or any cloud storage.


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## Steevo (Nov 18, 2012)

I have a 2TB drive that gets a backup of the pics and videos on a regular basis and I just got a new TP-Link router to test that has a FTP server built in and I added my 500GB USB drive to it and plan on backing up new pics and vids to it between the times I run full backups. 


I dislike losing data.


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