Date: Sun, 04 Jan 2009 01:26:50 +0000 From: Pete French <petefrench@ticketswitch.com> To: freebsd-stable@freebsd.org Subject: slow zvol performance compared to files on the same pool Message-ID: <E1LJHlS-000EO4-SB@dilbert.ticketswitch.com>
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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. -pete.
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