I'm running 3 Samsung HD103SJ 1TB and 1 Samsung HD103UJ 1TB under Lubuntu with zfs raidz2, using a HP ProLiant N54L (AMD N54L, 4GB RAM).

Moving a 10 GB file between 2 folders on the pool takes 15 minutes! "Downloading" a 20 GB file from the pool to the local computer took 40 minutes.

Reading and writing is very slow but I have no idea why.

zpool list
tank  3,62T   380G  3,25T    10%  1.00x  ONLINE  -

zpool status -v
pool: tank
state: ONLINE
scan: none requested
    tank        ONLINE       0     0     0
      raidz2-0  ONLINE       0     0     0
        sda     ONLINE       0     0     0
        sdb     ONLINE       0     0     0
        sdc     ONLINE       0     0     0
        sdd     ONLINE       0     0     0

errors: No known data errors

zfs list    

NAME                        USED  AVAIL  REFER  MOUNTPOINT
tank                        189G  1,59T  50,1K  /tank
tank/filme                 36,1G  1,59T  36,1G  /tank/filme
tank/os                    15,4G  1,59T  15,4G  /tank/os
tank/spiele                58,5G  1,59T  58,5G  /tank/spiele
tank/backups               79,5G  1,59T  4,77G  /tank/backups
tank/backups/new           66,0G  1,59T  66,0G  /tank/backups/new
tank/backups/old           8,73G  1,59T  8,73G  /tank/backups/old
  • 1
    Please show your zpool list and zpool status -v and zfs list. – ewwhite Oct 14 '14 at 16:07
  • @ewwhite I have updated the original question – moritzg Oct 14 '14 at 16:17

RAIDZ2 isn't going to be especially fast with 4 SATA disks... on a server with 4GB of RAM... with a weak processor... and without any level of ZFS tuning. ZFS mirrors would have been a better choice for a few reasons as well.

However, have you measured actually filesystem performance?

What are you expecting to see? That's about right, based on the gear you're describing.

  • How fast would the read speeds be with zfs mirror? CPU is at 50% and RAM at 3 GB... – moritzg Oct 14 '14 at 16:31
  • They would be faster as ZFS uses both sides of the mirror for reading – Fegnoid Oct 15 '14 at 8:39

In raidz2 you will get the IOPS of one disk. If you create two 2-way mirrors your write IOPS will double current ones and your read IOPS will increase four times. Besides that you should check if there is any firmware / update available for both types of disks, SATA/SAS controller, BIOS and NICs.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.