[Gluster-users] "Granular locking" - does this need to be enabled in 3.3.0 ?

[Pranith Kumar Karampuri]

Samuli,
>>As a side note I have to say that I have seen similar problems with
>>RAID-5 systems even when using them as non-replicated iSCSI target. In 
>>my experience it's definetly not good for hosting VM images.
    I think the performance problems he mentioned (I/O performance etc) were when a self-heal is triggered. If the replicate xlator is not loaded self-heal is never triggered. Could you raise bugs for the problems you are facing so that it will be improved in next releases. 

Pranith
----- Original Message -----
From: Samuli Heinonen <samppah at neutraali.net>
To: gluster-users at gluster.org
Sent: Fri, 20 Jul 2012 11:48:28 -0400 (EDT)
Subject: Re: [Gluster-users] "Granular locking" - does this need to be enabled in 3.3.0 ?

> 3) sanlock configured (this is evil!)

Just out of curiosity, can you please tell more why it is evil? I just 
found it out after your first post and want to know if there's any 
gotchas :)

> Though it doesn't corrupt data, the I/O performance is < 1% of my
> hardwares capability. Hopefully work on buffering and other tuning
> will fix this ? Or maybe the work mentioned getting qemu talking
> directly to gluster will fix this?

Have you tried setting performance.client-io-threads on if it makes any 
difference?

As a side note I have to say that I have seen similar problems with 
RAID-5 systems even when using them as non-replicated iSCSI target. In 
my experience it's definetly not good for hosting VM images.

-samuli
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