Date: Mon, 4 Sep 2017 15:25:18 +0100 From: Pete French <petefrench@ingresso.co.uk> To: freebsd-stable@freebsd.org Subject: Re: zfs, iSCSI and volmode=dev Message-ID: <203bd4d2-8c12-620a-8d0c-5c76d279174c@ingresso.co.uk> In-Reply-To: <ece540ba-8039-424f-8bad-c4266d70d84b@norma.perm.ru> References: <ece540ba-8039-424f-8bad-c4266d70d84b@norma.perm.ru>
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> I have an iSCSI production system that exports a large number of zvols > as the iSCSI targets. System is running FreeBSD 11.0-RELEASE-p7 and > initially all of the zvols were confugured with default volmode. I've > read that it's recommended to use them in dev mode, so the system isn't > bothered with all of these geom structures, so I've switched all of the > zvols to dev mode, then I exported/imported the pools back. > Surprisingly, the performance has fallen down like 10 times (200-300 > Mbits/sec against 3-4 Gbits/sec previously). After observing for 5 > minutes the ESXes trying to boot up, and doing this extremely slowly, I > switched the volmode back to default, then again exported/imported the > pools. The performance went back to normal. I too ghave a number of zvols exportes as iscsi, and I was using dev mode util I read this. AM going to experiment with switching back to default mode to see what happens. I also use dev mode for my virtualbox drives. Am going to try and test that too and see what I get. Interesting result though... -pete.
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