HAST local read performance?

[Karl Pielorz]

--On 5 March 2014 10:13:00 -0600 Mark Felder <feld at FreeBSD.org> wrote:

> 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.

Currently using async (makes no difference from fullsync - I'd guess that 
would only affect writes, not reads), and 'checksum none'

No atime enabled on the file system (ZFS) - the speed difference is very 
apparent with reading via dd (which is obviously raw-read only) - and on 
zpool scrubbing (which is 99% read with few writes) - if I deliberately 
'fail' the secondary (so not even those few writes are sent to the 
secondary) the speed remains the same.

It's certainly 'usable' - the only issue is with a few TB's of ZFS 
filesystem to scrub, it's rather slow through HAST (even when reads are 
happening only on the local machine).

Like you said you'd expect reads, from the local primary would be pretty 
similar to a local disk.

I guess with more devices online it'll pickup speed wise anyway.

-Karl