News [ars] nas drive users beware, SMR drives being stealth deployed into consumer lines tanking random io

[gorobei]

Buyer beware—that 2TB-6TB “NAS” drive you’ve been eyeing might be SMR

Hard drives were already bad at random access I/O—but SMR disks are worse.

arstechnica.com

techpod covers it for those to lazy to read https://techpod.simplecast.com/episodes/31-virtuals-on-virtuals-on-virtuals

the overlapping of the data elements in ShingledMagneticRecording means that there is a delay in random writes during a rebuild, so the os will fail out the drive and refuse to use it. so currently sold drives may not work in your existing zfs array. also not limited to WD as toshiba and seagate are doing the same.

 

[Shmee]

yikes. stay away.

 

[bononos]

Using NAS drives as ordinary desktop drives was always discouraged by manufacturers but this SMR thing is another new problem for users only very recently isn't it?

 

[gorobei]

this is specifically an issue for people running a nas with multiple drives in an array. the smr has to overwrite entire tracks to layer the shingles so to speak, functioning like flash memory mlc. to do this the drive stores your writes in a separate area and then later rewrites it in to the overlapped tracks. because it doesnt write immediately the zfs flags it as faulty and drops it from the array.

smr is fine for cold storage or something that is read only, but it cant be used for drives in an active nas that writes constantly and needs predictable bandwidth.