ZFS write speed

[jhell]

On 10/28/2010 03:30, S.N.Grigoriev wrote:
> 
> 
> 28.10.10, 01:54, "Stefan Bethke" <stb at lassitu.de>:
> 
>> Am 27.10.2010 um 22:51 schrieb S.N.Grigoriev:
>>  
>>  > Hi list,
>>  > 
>>  > I've got very low write speed using ZFS on a SATA disk.
>>  > My HDD configuration is:
>>  > ad4: 70911MB  at ata2-master UDMA100 SATA 3Gb/s
>>  > ad6: 78532MB  at ata3-master UDMA100 SATA 1.5Gb/s
>>  > ad8: 1430799MB  at ata4-master UDMA100 SATA 3Gb/s
>>  
>>  The EARS has 4k sectors, if I'm not mistaken.  I don't recall the eventual
>>  outcome, but there was a long thread on stable or hackers on how to ensure
>>  proper alignment and (minimun) 4k-sized writes to make sure the disk doesn't
>>  have to do a read-modify-write cycle, so try and search the archives.

Though this might play a small part in your write performance with the
EARS drives, this issue has more to do with the stat() calls and the ACL
involvement with ZFS. This was sort of solved in 8.1-STABLE and from 3
cases that I know about and 1 being my own... write/read speeds have
doubled from what can be seen to an effect of 8.1-RELEASE.

You may want to either upgrade to stable/8 or use one of the snapshots
from here:

ftp://ftp.freebsd.org/pub/FreeBSD/snapshots/201010/

> 
> Stefan,
> 
> thank you for your response. I'll try to find the topic you pointed.
> 
>>  > ad4 and ad6 are single-slice disks (UFS2 with soft updates)
>>  > 
>>  > ZFS configuration is following:
>>  > zpool create Z ad8
>>  > zfs create Z/music
>>  > zfs create Z/video
>>  > All ZFS parameters are default.
>>  > kern.maxvnodes = 1000000
>>  > 
>>  > To test my configuration I recursively copied from ad6 to ad8 two directories.
>>  > The first one contains MP3 files (average size = 10MB).
>>  > The second one contains AVI files (average size = 1GB). 
>>  > 
>>  > To compare performance I repeated above tests with ad8 using UFS2 with soft updates.
>>  > 
>>  > 18GB of MP3 files required 10m35s to copy to UFS2 and 21m40s to copy to ZFS.
>>  > 30GB of AVI files required 16m6s to copy to UFS2 and 1h2m39s to copy to ZFS.
>>  > 
>>  > I used for tests FreeBSD 8.1R amd64. Amount of RAM on my machine is 6GB.
>>  > 
>>  > Any tips?
>>  > 
>>  > -- 
>   


-- 

 jhell,v