[OmniOS-discuss] Restrucuring ZPool required?

[priyadarshan]

> On 18 Jun 2018, at 08:27, Oliver Weinmann <oliver.weinmann at icloud.com> wrote:
> 
> Hi,
> 
> we have a HGST4u60 SATA JBOD with 24 x 10TB disks. I just saw that back then when we created the pool we only cared about disk space and so we created a raidz2 pool with all 24disks in one vdev. I have the impression that this is cool for disk space but is really bad for IO since this only provides the IO of a single disk. We only use it for backups and cold CIFS data but I have the impression that especially running a single VEEAM backup copy job really maxes out the IO. In our case the VEEAM backup copy job reads and writes the data from the storage. Now I wonder if it makes sense to restructure the Pool. I have to admit that I don't have any other system with a lot of disk space so I can't simply mirror the snapshots to another system and recreate the pool from scratch.
> 
> Would adding two ZIL SSDs improve performance?
> 
> Any help is much appreciated.
> 
> Best Regards,
> Oliver

Hi,

I would be interested to know as well.

Sometimes we have same issue: need for large space vs need to optmise for speed (read, write, or both). We also are using, at the moment, 10TB disks, although never do RAID-Z2 with more than 10 disks.

This page has some testing that was useful to us: https://calomel.org/zfs_raid_speed_capacity.html

Section «Spinning platter hard drive raids» has your use case (although 4TB, not 10TB):

24x 4TB, 12 striped mirrors,   45.2 TB,  w=696MB/s , rw=144MB/s , r=898MB/s 
24x 4TB, raidz (raid5),        86.4 TB,  w=567MB/s , rw=198MB/s , r=1304MB/s 
24x 4TB, raidz2 (raid6),       82.0 TB,  w=434MB/s , rw=189MB/s , r=1063MB/s 
24x 4TB, raidz3 (raid7),       78.1 TB,  w=405MB/s , rw=180MB/s , r=1117MB/s 
24x 4TB, striped raid0,        90.4 TB,  w=692MB/s , rw=260MB/s , r=1377MB/s 

Different adapters/disks will change the results, but I do not thing ratio will change much.

It would be interesting to see how ZIL would affect that.


Priyadarshan