Some Western Digital WD Red HDDs Allegedly Use SMR, A Big Nono for NAS and RAID
Western Digital launched the WD Red line of hard drives and solid state drives specifically for NAS applications. The rigors of NAS involves not just near 24x7 uptime, but also the ability to work in RAID volumes, as most NAS servers ease the process for end users to set up RAID volumes for data redundancy. Data Storage-focused tech publication Blocks & Files alleges that some WD Red HDDs are shipping with shingled magnetic recording (SMR), a physical-layer data recording technique that makes the drive unfit for RAID, and in turn unfit for most serious NAS setups.
SMR is a recording technique that aims to achieve higher data density per platter, by partially overlapping tracks, by taking advantage of write tracks being wider than read tracks. Think of it as trying to cram a little more than one line of text per ruling, in a ruled notepad. The biggest trade-off with cramming in more data using SMR is a heavy loss in random write performance. The controversy of Western Digital shipping SMR WD Red drives came to light when Alan Brown, a network administrator with the UCL Mullard Space Science Laboratory, noticed that a brand new WD Red HDD kept getting kicked out of RAID arrays during resilvering (rebalancing of data with the addition of a new disk to an existing RAID array).
SMR is a recording technique that aims to achieve higher data density per platter, by partially overlapping tracks, by taking advantage of write tracks being wider than read tracks. Think of it as trying to cram a little more than one line of text per ruling, in a ruled notepad. The biggest trade-off with cramming in more data using SMR is a heavy loss in random write performance. The controversy of Western Digital shipping SMR WD Red drives came to light when Alan Brown, a network administrator with the UCL Mullard Space Science Laboratory, noticed that a brand new WD Red HDD kept getting kicked out of RAID arrays during resilvering (rebalancing of data with the addition of a new disk to an existing RAID array).