HAST local read performance?
Karl Pielorz
kpielorz_lst at tdx.co.uk
Wed Mar 5 14:10:07 UTC 2014
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...
-Karl
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