1

I actually have 4 SATA 3.0 disks on my home server and I want to organize them in order to have the best performance on my 10 RAID ZFS array

  • Seagate ST2000DL003 - Capacity : 2TB, Bandwith : 6GB/s, Cache : 64Mo, 5900 RPM, 4K physical sector
  • Seagate ST2000VN000 - Capacity : 2TB, Bandwith : 6GB/s, Cache : 64Mo, 5900 RPM, 4K physical sector
  • 2x Hitachi HUA723020ALA640 - Capacity : 2TB, Bandwith : 6GB/s, Cache : 64Mo, 7200 RPM, 512B physical sector

Should I put the Seagate's and Hitachi's drives together or should I make two Seagate/Hitachi mirrored array for having the best performance ?

Improve this question
1
  • Are you optimizing for best read performance or best write performance? Are you optimizing for sequential access or random access? Commented Apr 10, 2017 at 22:54

2 Answers 2

Reset to default
2

It is not generally recommended to mix 5900 and 7200 RPM disks in the same array. Anyway, I suggest you to match the same disks in each mirror. In short: make a mirror of the 5900 RPM devices + another mirror of the 7200 RPM devices, then stripe them together.

The most important thing to do is, anyway, to align the ZFS vdev/filesystem to a 4KB boundary, via the ashift=12 option.

Improve this answer
4
  • Should I set ashift=12 to both mirrored vdevs ? Or just for the 4k drive and ashift=9 to the other ? Commented Apr 9, 2017 at 15:25
  • If I remember correctly, ashift is a global parameter, rather than vdev-specific. Anyway, I would set it for the entire array. Commented Apr 9, 2017 at 18:38
  • ashift is disk-specific, at least on illumos, see for example wiki.illumos.org/display/illumos/… I would even argue that this is the only configuration that makes sense so that you can mix and match older and newer disks. Commented Apr 10, 2017 at 7:11
  • ashift is disk-specific also on ZFS on Linux. This can be configured through zdb if you are so inclined. Commented Apr 24, 2017 at 11:42
1

Ideally, you would use equally-sized and equally-spec'd disks in your array if you're concerned about performance or consistent operation.

Is there a reason you can't use the same type of drive?

Improve this answer
2
  • My disks are already equally sized... I talk about other factor like sector size, and speed of rotation Commented Apr 9, 2017 at 14:06
  • 1
    They may be equally sized, but they spin at very different speeds. Scheduling writes to these disks in an array is going to be troublesome, and we're going to be waiting on the 5400 RPM drives often enough to cause performance troubles. Commented Apr 9, 2017 at 18:16

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.