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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
NAME   SIZE  ALLOC   FREE    CAP  DEDUP  HEALTH  ALTROOT
tank  3,62T   380G  3,25T    10%  1.00x  ONLINE  -

zpool status -v
pool: tank
state: ONLINE
scan: none requested
config:
    NAME        STATE     READ WRITE CKSUM
    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
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    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
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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.

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  • 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
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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.

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