Add SSD to RAID-10 ZFS?

jmcorrea

jmcorrea

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Proxmox Subscriber
Jul 16, 2018
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www.netuy.net
Hello!

we have 2 servers with local ZFS pools. The pools are configured with the same type of disks. They have 3 x 120GB SSD and 4 x 4TB HDD.
I set the 3 SSD as a physical RAID 5, there runs Proxmox on one partition and ZFS logs and cache on 2 other partitions. Then, with the 4 HDD I set up a RAID10:

Pool 1:
Code: 
root@server-7:~# zpool status -x
all pools are healthy
root@server-7:~# zpool status
  pool: storage-pool
 state: ONLINE
  scan: scrub repaired 0B in 24h13m with 0 errors on Mon Apr 15 00:37:44 2019
config:

    NAME          STATE     READ WRITE CKSUM
    storage-pool  ONLINE       0     0     0
      mirror-0    ONLINE       0     0     0
        sdb       ONLINE       0     0     0
        sdc       ONLINE       0     0     0
      mirror-1    ONLINE       0     0     0
        sdd       ONLINE       0     0     0
        sde       ONLINE       0     0     0
    logs
      sda4        ONLINE       0     0     0
    cache
      sda5        ONLINE       0     0     0

errors: No known data errors
root@server-7:~# zpool list
NAME           SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
storage-pool  7.25T  3.41T  3.84T         -    39%    47%  1.00x  ONLINE  -

Pool 2:
Code: 
root@server-8:~# zpool status
  pool: storage-pool
 state: ONLINE
  scan: scrub repaired 0B in 183h36m with 0 errors on Sun Apr 21 16:01:40 2019
config:

    NAME          STATE     READ WRITE CKSUM
    storage-pool  ONLINE       0     0     0
      mirror-0    ONLINE       0     0     0
        sdb       ONLINE       0     0     0
        sdc       ONLINE       0     0     0
      mirror-1    ONLINE       0     0     0
        sdd       ONLINE       0     0     0
        sde       ONLINE       0     0     0
    logs
      sda4        ONLINE       0     0     0
    cache
      sda5        ONLINE       0     0     0

errors: No known data errors
root@server-8:~# zpool list
NAME           SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
storage-pool  7.25T  4.28T  2.97T         -    47%    59%  1.00x  ONLINE  -

Now I have 4 x 1TB SSD disks and I would like to add them to the RAIDs 10, 2 SSD on each server.

Do you think this is a good way to use this SSD? Is there a better way to use them on our current configuration?

Any advice is welcome, thank you very much!

Best regards,

Juan
 
Hi,

it is generally not recommended to use ZFS in combination with Raid Cards.
ZFS has it own cache management and the transparent raid cache will interfere.
 
Hello @wolfgang!
Yes, i read about that, that is why the SSD RAID 5 is not ZFS, is a good old LVM.
I been doing some testing and research and it seems that the way to get the most of the SSD disks is to create a new zpool for them, because if i add them to the current HDD zpool the speed i get from them will be the same as if they were HDD, is this correct?
Thank you very much!
Best regards,
Juan
 
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