# RAID 0 setup: What do I need?



## JrRacinFan (Feb 15, 2008)

Hiya guys. In a RAID 0 setup, do the hard drives specs and capacity have to match? Let's say 3x320GB's? Or can they be like 2x160GB's and 1 500GB?


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## Hawk1 (Feb 15, 2008)

They can be different sizes, but the raid will only be the size of the smallest drive. So 3x160GB = 480GB raid for those three drives in your second example.


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## AddSub (Feb 15, 2008)

> do the hard drives specs and capacity have to match?



No, you can mix and match all you want. Depending on the hard disk controller you can mix and match drive sizes, drive RPMs, even interfaces, mixed SATA/PATA arrays.


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## Kreij (Feb 15, 2008)

The RAIDed partitions have to match, not necessarily the drives.
So you could have the two 160s and a 160 partition on the 500 RAIDed together.


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## JrRacinFan (Feb 15, 2008)

Ok so going by Kreij's example the 500GB would have to be 3 partitions (=~480GB) along with 1 partition on each 160GB drive "??"


EDIT: Also, in all actuality if I wanted to setup my drives the 120 and 80 in a Raid 0 I could? They are PATA.


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## Hawk1 (Feb 15, 2008)

JrRacinFan said:


> Ok so going by Kreij's example the 500GB would have to be 3 partitions (=~480GB) along with 1 partition on each 160GB drive "??"



The 500GB would have to be at least 2 partitions: 1x 160GB for the RAID, and the rest (remaining 340GB) however you want it (storage etc).


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## AddSub (Feb 15, 2008)

> The RAIDed partitions have to match, not necessarily the drives.
> So you could have the two 160s and a 160 partition on the 500 RAIDed together.



Dude, don't confuse him. 

JrRacinFan, as far as the OS is concerned, you can setup your partitions any way you like, since RAID0 will be seen as a single drive, no matter how many actual physical drives you use. You have the same limits and freedoms with partitioning as you would otherwise. And yes, you can add additional disks without them being in the RAID array.


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## CrAsHnBuRnXp (Feb 15, 2008)

http://forums.techpowerup.com/showthread.php?t=43572&highlight=RAID+Arrays+Explained


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## tiys (Feb 15, 2008)

Sorry, but I have no knowledge on RAID'ing stuff


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## DanishDevil (Feb 15, 2008)

Not necessarily.  How many drives do you want RAIDed?

It basically goes like this.  And correct me if I'm wrong, as I haven't actually raided anything.

Creating a partition creates a "new drive."  You can raid as many drives as you want, but the sizes all have to match.  So, you could raid the first two drives, and have the last for storage, or you could partition the last 500GB drive to a 160GB drive and whatever you have left, and raid the first two drives, and the smaller partition of the last drive, leaving the rest of the drive for storage.

FYI: The cheapest drives you can get right now (price per GB) are 750GB drives.

What drives do you have now?  Or are you starting from scratch?


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## Mussels (Feb 15, 2008)

the simplest version is:

The partitions have to match. For best performance/ease of use/less wasted space, two matching drives is best. 

For speed reasons, two drives of the same type are reccomended (sata/pata/scsi)

If the two drives have totally different speeds, the slower one will hamper the faster one.


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## AddSub (Feb 15, 2008)

> EDIT: Also, in all actuality if I wanted to setup my drives the 120 and 80 in a Raid 0 I could? They are PATA.



Yes, if that particular disk controller supports PATA arrays, and most do.


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## JrRacinFan (Feb 15, 2008)

Just researching for some information. I have never setup a RAID array before, and all the information here has helped me alot so far.

So a 160+160+500 would turn out being a 480GB RAID 0 setup with 340 left on the 500. I think i got this so far.

So in essence 1TB+1TB+500GB= 1.5TB Raid 0 array with 2 500GB partitions left?


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## surfsk8snow.jah (Feb 15, 2008)

But there's 0 point in taking one physical HDD, partitioning it into, say, 3 partitions, and RAIDing two of them together. That's... useless, slower, inefficient. 
The idea of RAID arrays is to increase performance & redundancy, so the topic only usefull applies to physical HDDs.

The majority of your RAID controllers (e.g. - Onboard nVidia controllers) will basically trim the larger drive to the size of the smaller drive. Therefore your example would turn into (1)Logical 480GB drive, with far better performance than one of them. However, you will "lose" the rest of the space on the 500GB HDD. 
However, what was said about proprietary RAID cards is true; they are very much customizable.


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## surfsk8snow.jah (Feb 15, 2008)

JrRacinFan said:


> So in essence 1TB+1TB+500GB= 1.5TB Raid 0 array with 2 500GB partitions left?



Yes. Accessing those partitions is another story. Generally, you wouldn't be able to.


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## Mussels (Feb 15, 2008)

JrRacinFan said:


> Just researching for some information. I have never setup a RAID array before, and all the information here has helped me alot so far.
> 
> So a 160+160+500 would turn out being a 480GB RAID 0 setup with 340 left on the 500. I think i got this so far.
> 
> So in essence 1TB+1TB+500GB= 1.5TB Raid 0 array with 2 500GB partitions left?



i would leave the 500GB out of it. when you RAID, its tied to the controllers chipset and you DO have to format. So if your mobo dies, you lose the data unless you get the exact same board back.

I would raid 0 the two 160GB drives for OS/games, leaving the 500GB as storage/backup.


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## JrRacinFan (Feb 15, 2008)

I understood that surf, and I would say I pretty much got all information really needed on RAID arrays just from how little is in this thread.

Oh I understand now Mussels and it was just a theorhetic example.


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## Hitsugaya_Toushirou (Feb 15, 2008)

I don't recommend using RAID0 since the decrease in reliability for a 1-2% performance increase is not worth it but i guess that wasn't what you wanted know. RAID-0 is the most meaningless RAID out of all that RAID levels.


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## DanishDevil (Feb 15, 2008)

No.  Raid 0 is data striping.  That is, if your files consist of:  "ABCDEFGH", this is how it will play out:

Drive 1:  "ACEG"
Drive 2:  "BDFH"

Therefore, it increases performance, but if one fails, you're boned.  Therefore, since they read as one drive, if you wanted 3 drives in your RAID 0 array, it would play out like this:

Drive 1:  160GB
Drive 2:  340GB

Drive 1 would consist physically of the two 160s and 160 of the 500, but windows would only allow you to store 160GB of files on it.

Or, for your second example:

Drive 1:  500GB (3 raid partitions)
Drive 2:  500GB
Drive 3:  500GB


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## Kreij (Feb 15, 2008)

JrRacinFan said:


> Just researching for some information. I have never setup a RAID array before, and all the information here has helped me alot so far.
> 
> So a 160+160+500 would turn out being a 480GB RAID 0 setup with 340 left on the 500. I think i got this so far.
> 
> So in essence 1TB+1TB+500GB= 1.5TB Raid 0 array with 2 500GB partitions left?



Yes, you could even RAID0 the two left over 500GB partitions into another array, so you would have a 1.5TB RAID0 array (3 x 500 on 3 drives) and a 1TB RAID0 arrays (2x 500GB partitions that were left over).


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## Mussels (Feb 15, 2008)

JrRacinFan said:


> I understood that surf, and I would say I pretty much got all information really needed on RAID arrays just from how little is in this thread.
> 
> Oh I understand now Mussels and it was just a theorhetic example.





no problem. i just like empasising the downsides, as back on Nforce 2 i nearly lost 2x120GB of raid due to the mobo dying - found a cheap PCI SATA card that was compatible, but i'll never forget the fact no one warned me about it at the time.


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## Hitsugaya_Toushirou (Feb 15, 2008)

It can sometimes even decrease performance since the overhead from the RAID controller can cause a decrease in performance.

The only place you'll see an increase in performance is in synthetic tests.


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## JrRacinFan (Feb 15, 2008)

OK so RAID 0 is basically doing an identical backup? RAID 1 is a combination of 2 drives for performance? 

I thought it was the other way around. Help me with that guys please!

EDIT: off topic @ kreij ....

I liek the morse code in your sig! TPU is pretty darn sweet!


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## Mussels (Feb 15, 2008)

no no. 

Raid 0 is speed.

RAid 1 duplicates files - saves you the risk of losing data from a dead drive, but does nothing to prevent user error (aka if a file deletes off one, it delets off both)

I find raid 0 useful if HDD speed is critical (lots of network transfers, media encoding etc) and raid 1 useful only of you fear drives dying all the time.


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## JrRacinFan (Feb 15, 2008)

Thats what I thought.


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## surfsk8snow.jah (Feb 15, 2008)

This is the best website to help understand RAID:
http://www.acnc.com/raid.html

This one is also good:
http://en.wikipedia.org/wiki/RAID

Mussels is correct. 0 is for performance (not REALLY a real RAID array technically), 1 is for redundancy (kinda like a backup).


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## Kreij (Feb 15, 2008)

RAID0 can give you up to a 30% performance increase. I have two seagate drives that when I run hdtach they easily beat out a Raptor on overall transfer of large files.

If you RAID0 for performance you want to make sure you do regular backups in case one dies as you will lose the data on both.

If most of what you do is gaming, you are better off going with good drives and putting them in RAID1 for data protection.


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## JrRacinFan (Feb 15, 2008)

Ok I think i'm good guys. Thanks for all the help!!!!


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## Kreij (Feb 15, 2008)

JrRacinFan said:


> Ok I think i'm good guys. Thanks for all the help!!!!



That doesn't mean we are going to quit arguing about it though 

I have two 320s in RAID0 for 640GB total.
I have two 320s in RAID0 for 640GB total in a NAS device for backup.

Seems to work pretty well.


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## IggSter (Feb 15, 2008)

Ok here is my hat in the ring:

Firstly, raid can be performed in software and in hardware.

Software:
Windows 2000 and XP (not sure about Vista) can create raid arrays without the need for a hardware raid controller.

These arrays can be made up of whole or parts or any disk (sata or pata) that are present in your system. NOTE there are some limitations to this which are detailed on the MS website.

The downside to using software raid is a small increase in CPU usage (approx 3-5%)

Hardware:
Your system will need a raid controller of some description either on mobo chipset or as an add-in card.
Most common raid controllers work on a 'whole drive' basis, that is you can't add a part of a drive. This means that the controller will 'resize' all disks down to the smallest in that particular array.

Raid types:

0: Stripping. (my 2nd favorite) This is where 2 or more physical hard drives are turned into one virtual harddrive with the total capacity available. This gives the best performace gain as half the data is written to one drive and the other half is written to 2nd (in a 2 drive array) but should any physical drive fail, the virtual drive also fails.

1: Mirroring. (I see this as pretty pointless for the typical home user/gamer ) This is where 2 physical drives are turned into one virtual hard drive with only half the total capacity available. This gives negligible performance gains for writing as all the data has to be written to each drive but gives better performance for reads (not as much as stripping but more than non-raid drive) as the controller can read the data from both drives.
If one physical disk fails the logical disk will still be operational.

I will skip raid levels 0-1 and 1-0 as they require a minimum of 4 drives to operate but basically its stripping and mirroring at the same time (performance and reliability)

5: Stripping with ditributed parity. (my favorite) Needs 3 or more drives to create an array and data is stripped across all drives. However, parity information is also written across all 3 drives so in the event of one drive failing, the lost data is automatically rebuilt from the parity information on the remaining 2 drives. Downside are that total capacity is 2 out of 3 drives (100gig+100gig+100gig=200gig) and also should a drive fail the performance is abysmal until the missing data is rebuilt. This raid method gives nearly the same performance gains as raid 0 while also giving you the reliability of raid 1.

It should also be noted that the more drives you have in an array the more performance you will get (until you hit a controller/cpu/mem bandwidth bottleneck)

My preferred configuration is:

C: Normal physical hard drive with windows install
D: Raid 0 array containing applications/games and data that I have a backup of (also put swap file on here)

or

C: Raid 5 array with everything on it.


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## JrRacinFan (Feb 15, 2008)

LMAO ....

@ kreij
Off topic, I mentioned it before but you didn't respond. I like your morse code message in your sig.

Thanks Iggster! I bet you copy and pasted that word for word ...


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## IggSter (Feb 15, 2008)

JrRacinFan said:


> LMAO ....
> 
> @ kreij
> Off topic, I mentioned it before but you didn't respond. I like your morse code message in your sig.
> ...




LOL, I wish, I do this shit on almost a daily basis - thats why I missed your last post saying thanks to everyone.


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## Kreij (Feb 15, 2008)

JrRacinFan said:


> LMAO ....
> 
> @ kreij
> Off topic, I mentioned it before but you didn't respond. I like your morse code message in your sig.
> ...



I did respond to the first person who saw it (don't remember if that was you. I need to change it now to give observant TPU'ers something else to think about 

Here is a little more "helpful" information on RAID0 ...

PROS :
Using RAID0 will allow double the capacity of a single drive and increase performance.
Saying you are running RAID0 will increase the size of your e-P by about 1 inch.
Most girls like RAID0 better than RAID1 or RAID5, they are all for performance.

CONS:
If you update your BIOS you may have to fiddle around to make it see the array again (no big deal, it won't be lost).
If your RAID0 array crashes and you lose all your data, your e-P will shrink by 2 inches.
If you meet a girl who is rather redundant, she will like RAID1 better.

Your call


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## JrRacinFan (Feb 15, 2008)

So essentially I could RAID 0+1 4 500GB Drives?

That would give me 1TB RAID Array + 1TB RAID backup?

EDIT: comment about redundant ....

Married ....  and no it wasn't me I just noticed it.


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## CrAsHnBuRnXp (Feb 15, 2008)

I did post a link on the first page that leads to the RAID guide on this forum. No one saw it?


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## Mussels (Feb 15, 2008)

JrRacinFan said:


> So essentially I could RAID 0+1 4 500GB Drives?
> 
> That would give me 1TB RAID Array + 1TB RAID backup?



yes.


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## JrRacinFan (Feb 15, 2008)

I saw it Crashburn, and read it.


Oh trust me mussels I have no plans on doing this yet. But when I do, all of TPU will know when I start another thread LOL


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## Kreij (Feb 15, 2008)

Yes, 4x 500GB in RAID0+1 would give you two RAID0 arrays for performance that are duplicates of each other (RAID1)

However, I think that the consensus is that if you have 4 drives you would be better off going RAID5. (I could be wrong on that).


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## Mussels (Feb 15, 2008)

Kreij said:


> Yes, 4x 500GB in RAID0+1 would give you two RAID0 arrays for performance that are duplicates of each other (RAID1)
> 
> However, I think that the consensus is that if you have 4 drives you would be better off going RAID5. (I could be wrong on that).



i plan on running 5x500 in raid 5.

If i'm right, that gets me 2TB of (fast) space, with one 500GB for parity, yes?


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## IggSter (Feb 15, 2008)

JrRacinFan said:


> So essentially I could RAID 0+1 4 500GB Drives?
> 
> That would give me 1TB RAID Array + 1TB RAID backup?
> 
> ...




Just to clarify this a little:

if you have 4 x 500GB and use raid  0-1 you will have a total of 1TB of usable space that will allow ONLY 1 drive to fail - then the array falls back to being a raid 0 array. 
Raid 0-1 give the best performance.

With raid 1-0  2 drives can fail (it depends which drives though) and the array will still operate.
Raid 1-0 gives the best reliability.


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## Mussels (Feb 15, 2008)

dont forget me, i asked about raid 5 on those drives too


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## IggSter (Feb 15, 2008)

Mussels said:


> i plan on running 5x500 in raid 5.
> 
> If i'm right, that gets me 2TB of (fast) space, with one 500GB for parity, yes?




Yes that is correct, with raid 5 the parity is striped across all disk so any one drive can fail and the array will still operate.

Raid 3 is similar in that it gives the same amount of usable space but the parity is written to the 5th drive only (this type of raid is pretty much unused as raid 5 is easier to setup and gives equal performance when in normal operation and does not suffer the terrible performance the hits raid 3 when a drive fails)


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## Hawk1 (Feb 15, 2008)

Just remember if you go SATA RAID, to configure in your BIOS to SATA as RAID (the other options are IDE and AHCI). When you do this and your ready to install XP you will have to have a SATA/RAID driver Floppy disk ready (unless you do a slipstream install disk) and hit F6 during the first few seconds of the OS install starting up, or it will not see any of the drives.  XP does not have SATA drivers built in (SATA was before its time).


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## IggSter (Feb 15, 2008)

Quit ninja edit post:

If you have very deep pockets and have 2,4,6 etc drives available you can always consider duplexing your raid array.

this is where you put half the disks on one raid controller and the other half on another (you will need 2 identical raid add-in cards for this)

You can then either mirror (raid 1) or mirror/stripe (raid 10) across both controllers

This is very effective if you are using 6 or more disks as this would normally cause a bottleneck with 1 controller. It also gives the added advantage of allowing one controller to fail while keeping the array running.

(The best raid cards to get for this are ones with onboard cache as basically all disk writes go directly to this cache and as long as the filesize is less than cache size the write will be nearly instant. This also can work for reads as these controllers can be configured to cache recently accessed files)

And if you have very very very deep pockets just buy a RamSan and flip the bird to everyone you know.


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## Mussels (Feb 15, 2008)

I'll be using an external controller (e-sata cage with port multiplier)

Raid 5 sounds good, as ANY of the drives can fail (but only one) without losing anything. At the same time, 2TB with the speed of 5 drives sounds.... pretty sweet.


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## IggSter (Feb 15, 2008)

Mussels said:


> I'll be using an external controller (e-sata cage with port multiplier)
> 
> Raid 5 sounds good, as ANY of the drives can fail (but only one) without losing anything. At the same time, 2TB with the speed of 5 drives sounds.... pretty sweet.



If a drive does fail you can also remove the faulty one, replace it with a new one and rebuild the array (either in the bios or in background mode) and you are back to a fully redundant 5 drive solution.


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## JrRacinFan (Feb 15, 2008)

Interesting!


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## Hitsugaya_Toushirou (Feb 15, 2008)

Kreij said:


> RAID0 can give you up to a 30% performance increase. I have two seagate drives that when I run hdtach they easily beat out a Raptor on overall transfer of large files.
> 
> If you RAID0 for performance you want to make sure you do regular backups in case one dies as you will lose the data on both.
> 
> If most of what you do is gaming, you are better off going with good drives and putting them in RAID1 for data protection.



RAID0 gives up to 40% performance increase on synthetic tests only. In applications and games it will only increase performance by 2% in some cases and you can find that performance can decrease by up to 2% in some cases as well from the overhead from the RAID controller.

If you want proof, go here: http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=1

Also, even if you use a very good external RAID controller, there is very little difference in the outcome except the overhead might be an unoticable fraction less.


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## Mussels (Feb 15, 2008)

Hitsugaya_Toushirou said:


> RAID0 gives up to 40% performance increase on synthetic tests only. In applications and games it will only increase performance by 2% in some cases and you can find that performance can decrease by up to 2% in some cases as well from the overhead from the RAID controller.
> 
> If you want proof, go here: http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=1
> 
> Also, even if you use a very good external RAID controller, there is very little difference in the outcome except the overhead might be an unoticable fraction less.



I'm using mine to simply rape gigabit network. Giga can do over 100MB/s, my drives cap it around 50-60MB. 2x drives in raid lets me double the throughput 

5x drives in raid 5 lets me saturate it, which makes me feel warm, fuzzy, and secure against data loss.


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## Hitsugaya_Toushirou (Feb 15, 2008)

Mussels said:


> I'm using mine to simply rape gigabit network. Giga can do over 100MB/s, my drives cap it around 50-60MB. 2x drives in raid lets me double the throughput
> 
> 5x drives in raid 5 lets me saturate it, which makes me feel warm, fuzzy, and secure against data loss.



Gigabit network goes up to 125MB/s but using RAID won't necessarily allow you to use all of it so you won't get all of a speed increase in network transfers but it'll be more than applications and games i guess but with a decrease in reliability.

Just from my personal testing i found that even average throughput operations goes by this rule i made (assuming you have no other bottlenecks):
Slowest HHD Bandwidth x (1+0.20^(1/(Number of HHD - 1))
So even with 5 HHD with 60MB/s bandwidth then even pure throughput operations like transferring over the network will only give about 100MB/s but at the cost of a massive reduction in reliability of your drives and near 0% performance increase in applications and games.

Though those are my personal tests so you don't have to take if you don't want to.


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## grunt_408 (Feb 15, 2008)

I currently have a 300 Gb Hdd How much faster would my pc be with a second 300 Gb.?


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## IggSter (Feb 15, 2008)

Hitsugaya_Toushirou said:


> RAID0 gives up to 40% performance increase on synthetic tests only. In applications and games it will only increase performance by 2% in some cases and you can find that performance can decrease by up to 2% in some cases as well from the overhead from the RAID controller.
> 
> If you want proof, go here: http://www.anandtech.com/storage/showdoc.aspx?i=2101&p=1
> 
> Also, even if you use a very good external RAID controller, there is very little difference in the outcome except the overhead might be an unoticable fraction less.




I'm sorry but but I have to correct a few things here:

#1 the anandtech article is dated July 1st, 2004 so those figures are completely useless now.
#2 the system specs are pityful for testing a raid setup (again due to the age of test). There would be so many bottlenecks in that system.
#3 the testing method fo games is totally flawed. Loading a level in a game is hardly a comprehensive real life test.


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## IggSter (Feb 15, 2008)

Craigleberry said:


> I currently have a 300 Gb Hdd How much faster would my pc be with a second 300 Gb.?



There is no hard and fast answer to this unfortunately as it depends on so many other factors but i will try and give you a general feeling for what to expect:

If you have a raid array and you run any form off application that thrashes the disk (BF2 is one that springs to mind also any database/video editing-encoding apps) you will notice your PC will feel far more responsive in general.

If you move a lot of large chunks of data around (100's of MB or more) copy times will be greatly reduced (if copying from raid to raid)

Large application load time will be reduced by a noticable amount especially so if application consists of large files (the smaller the files the less the benefit)

Defragmentation of drive becomes much less of an issue ie, your drives will need defragmenting less often and the slow down due to defragmentation is much less noticable.

Here is a couple of real life examples from one of my PCs

PC has C: which is a normal 160gig sata2 drive and R: which is a 160gig raid0 array (2 x 80gig drives)

Please note this is a working PC and was last given a fresh install of XP around 18mths ago.

Load time of a game called Eve:

c: 12sec

r: 8sec

Copy time of an acronis 3.8gig disk image:

r:\folder1 > r:\folder2 (this will test combined read/write of raid) - 2m 34sec

c:\folder1 > c:\folder2 (this will test combined read/write of sata2) - 3m 1sec

Nice improvement there I think you will agree.

r: > c: (tests read from raid and write to sata2) - 1m 12sec

c: > r: (tests read  from sata2 and write to raid) -1m 35sec

This shows that reads from raid are faster than using standard sata2 drive and im sure that if I had 2 raid arrays available on same PC copying from one to the other would produce a figure of well below 1m.

I hope that helps.


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## Hitsugaya_Toushirou (Feb 15, 2008)

IggSter said:


> There is no hard and fast answer to this unfortunately as it depends on so many other factors but i will try and give you a general feeling for what to expect:
> 
> If you have a raid array and you run any form off application that thrashes the disk (BF2 is one that springs to mind also any database/video editing-encoding apps) you will notice your PC will feel far more responsive in general.
> 
> ...



You didn't mention the HHDs used. The 80GB HHD could be originally higher performance than the 160GB, which means the results difference is enlarged unfairly. Well, no doubt transferring data between the RAID system and a separate source/destination will get a reasonable boost in timings but you need a more controlled comparison since these results could be exaggerated.


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## Mussels (Feb 15, 2008)

Hitsugaya_Toushirou said:


> Gigabit network goes up to 125MB/s but using RAID won't necessarily allow you to use all of it so you won't get all of a speed increase in network transfers but it'll be more than applications and games i guess but with a decrease in reliability.
> 
> Just from my personal testing i found that even average throughput operations goes by this rule i made (assuming you have no other bottlenecks):
> Slowest HHD Bandwidth x (1+0.20^(1/(Number of HHD - 1))
> ...



no reliability loss due to raid 5 - not raid 0. raid 5 enahcnes the reliability.
I am NOT using it for games - its for storage and backups, and moving 1TB of data takes a shitload of time when upgrading/installing more drives internally.


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## IggSter (Feb 15, 2008)

Disks are: 

Samsung HD160JJ with Noiseguard disabled (fairly typical Sata2 drive)

Raid drives: Hitachi Deskstar 7K160 80GB SATA-II 8MB x 2 (again fairly typical drives)

And with regard to Gigabit Ethernet, it is usual to run this in full duplex mode and thus get a max sustained throughput of 250MB/sec (this depends entirely on the NIC/Switch/Router)


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## Mussels (Feb 16, 2008)

IggSter said:


> Disks are:
> 
> Samsung HD160JJ with Noiseguard disabled (fairly typical Sata2 drive)
> 
> ...



full duplex means absolutely nothing. you cannot get faster than 125MB/s.

Full duplex means it can do full speed both ways at once, which has always been a bukllshit advertising scam - you CANT get full speed both ways unless you're using a lot of hard drives on each end (seperate ones for each transfer) and its both ways at once - its 2x125 (different directions) NOT 1x250MB/s (double speed transfers)

Anyone who argues that point, its like saying a quad core is twice as fast as a dual core.


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## IggSter (Feb 16, 2008)

That is partly true but:

1. full duplex disables collision detection on an ethernet interface, therefore a network interface never has to listen for collisions or retry = greater throughput.

2. full duplex allows a network interface to send and receive at the same time, and for every packet you send your will get an ACK (as minimum) returned. Therfore even if you are only sending a file, you will be receiving a shed load of data back = greater throughput.

So in essence in half duplex you have 125MB avail to send and receive, while in full duplex you have 125MB to send AND 125MB to receive (think along the lines of a bridge across a river with only one lane vs a bridge with 2 lanes and there is traffic crossing both ways. The two lane bridge will be much faster.


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## surfsk8snow.jah (Feb 16, 2008)

Mussels said:


> Anyone who argues that point, its like saying a quad core is twice as fast as a dual core.



What, it's not??


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## Mussels (Feb 16, 2008)

IggSter said:


> That is partly true but:
> 
> 1. full duplex disables collision detection on an ethernet interface, therefore a network interface never has to listen for collisions or retry = greater throughput.
> 
> ...



yes. thats 2x125. NEVER can you reach 250MB/s, as each direction is capped at 125 maximum.
You cant even get gigabit thats not full duplex, its been 5 years or more since ive seen a half duplex network switch for sale.
half duplex is LESS than 125, full is 125. you mentioned 250, and i'm just making sure no one gets that impression.


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