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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. Commented Oct 14, 2014 at 16:07
  • @ewwhite I have updated the original question Commented Oct 14, 2014 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... Commented Oct 14, 2014 at 16:31
  • They would be faster as ZFS uses both sides of the mirror for reading Commented Oct 15, 2014 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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