Date: Wed, 05 Mar 2014 10:13:00 -0600 From: Mark Felder <feld@FreeBSD.org> To: freebsd-geom@freebsd.org Subject: Re: HAST local read performance? Message-ID: <1394035980.8640.90922737.615AFA56@webmail.messagingengine.com> In-Reply-To: <B62B94E66C2B63D3894AB7DF@Mail-PC.tdx.co.uk> References: <B62B94E66C2B63D3894AB7DF@Mail-PC.tdx.co.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Mar 5, 2014, at 8:08, Karl Pielorz wrote: > > Hi, > > I have a couple of FreeBSD 10 systems I've setup HAST on - this seems to > work well, but I've noticed the read performance of local /dev/hast/* > devices is around half of the normal raw device? > > e.g. a dd from an SSD as /dev/da0 nets around 220Mbyte/sec - the same dd > run against the same device when setup with hast (i.e. /dev/hast/disk1) > only nets around 110Mbyte/sec. > > I realise another layer is going to affect performance (and this may just > be the price you have to pay) but is there anything likely tunable for > this? > > If I fail the other node (so I'm running the test against a 'degraded > primary') it's still as slow [as you'd kind of expect, as reads were/are > only local] > > I've setup ZFS on top of the hast devices - again this seems to work OK, > but you can really see the performance difference when doing a pool scrub > on hast backed devices vs. the raw ones... > Which HAST replication mode are you using? Fullsync? Do you have atime enabled on that filesystem? I'd expect it to act like a local disk without any significant penalties unless you're doing writes and they're waiting to be synced before the next read.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1394035980.8640.90922737.615AFA56>