Pete French wrote:
I was experimenting with iscsi earlier, using both a flat file as the
backing store and also a zvol. I noticed that the zvol was giving me
dreadful performance - reading at about 20 meg/second and writing at
about 12. the fklat file gives about 45 meg/second both ways.
i thouht it was to do wuth the iscsi layer, but I then tried it using
dd on the machinbe itself and got the same results. it seems very
curious - I am creating both the filesystem for the iscsi file and the
zvol on the same pool, so the underlying discs (4 x 15k SCSI drives on
U320) are the same in both places, as is the pool.
anybody got any opinions ? this is on 7.1-RC2, but I have nothing else
to compare it to.
On 7.x (where ZFS is really quite broken for server use - don't waste
too much time on it) the ZVOL code did an "fsync" after every single
block write. Its a testament to your fast disks that you got as high as
12mb/s. I don't know why your read speed was so bad, but you should try
again on 8-current as numerous fixes and improvements have happened.
- Andrew
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