Hi,

I'm running Opensolaris 2009.06, and I'm facing a serious performance loss with 
ZFS ! It's a raidz1 pool, made of 4 x 1TB SATA disks :
        zfs_raid    ONLINE       0     0     0
          raidz1    ONLINE       0     0     0
            c7t2d0  ONLINE       0     0     0
            c7t3d0  ONLINE       0     0     0
            c7t4d0  ONLINE       0     0     0
            c7t5d0  ONLINE       0     0     0

In the beginning, when the pool was just created (and empty !), I had the 
following performances :
 - Read : 200 MB/s
 - Write : 20 MB/s (10 MB/s with compression enabled)
These performances were OK at this time.

However, after 2 months of production use, and a volume of data of 1TB only, 
the performances are near :
 - Read : 5 MB/s 
 - Write : 500 KB/s !!!! 
The write speed is so low that is breaks any network copy (Samba or SFTP). The 
only solution I found to copy large files to the pool without outages is to use 
SFTP via Filezilla, with the activation of the bandwich limit (limit=300 KB/s) 
!!!

In this pool, I have 18 filesystems defined :
 - 4 FS have a recordsize of 16KB (with a total of 100 GB of data)
 - 14 FS have a recordsize of 128KB (with a total of 900GB of data)
There is a total of 284 snapshots on the pool, and compression is enabled.
There is 3 GB of physical RAM.

The usage of the pool is for daily backups, with rsync. Some big files are 
updated simulteanously, in different FS. So, I suspect a huge fragmentation of 
the files ! Or maybe..., a need of more RAM ??

Thank you for any thoughts !!
Philippe
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