[Gluster-devel] Full bore.

Kevan Benson kbenson at a-1networks.com
Thu Nov 15 17:39:56 UTC 2007

Chris Johnson wrote:
>      Hi again,
>      Ok, now have CentOS5 on the two DELL front ends to this SATA
> Beast thingy.  I have gluster enhanced fuse on both and glusterfs
> 1.3.5 on both.
>      Performance is still way below NFS.  I have turned on
> write-behind and read-ahead.  And with fuse it's a little faster. but
> not significantly.  To get more out of this it's pretty ovious I need
> to do unify if I want BIG space, maybe striping.  If I  want high
> availability I need AFR (that works with unify?).  And if I want to
> use the second DELL front end I'm probably going to need locking if
> they share drives.  Self healing works, right?  Wasn't there discussion
> about a potential problem not long ago?
>       Sound about right?

Pretty much.  The self heal discussion was about edge cases.  It works 
for most situations you'll see it in.

AFR and Unify (and striping) are stackable, layer as many as you want 
(AFR dual unified AFR's if you want.

>       I think I'm seeing from the glusterfs wiki that the order
> in which things are defined in the config files matters.  It's a bit
> unclear to me what the real order of things should be.

It's doesn't REALLY matter too much, unless it's a client config and you 
aren't explicitly defining the share to load (then it grabs the last 

Most translators specified that rely on other volumes have you 
specifically state which volumes they are using.  The only way I see 
order mattering there is that the subvolumes used by a translator may 
need to be defined above the location they are used in a translator. 
I.e. define share1 and share2 before you include them in an AFR/Unify. 
I'm not sure this is required, but it's probably easier to read the 
configs if you do it anyways.

>      Oh, this is ext3 with xattr turned on.  But we could use Reiserfs
> if that would help.  I may run tests on that as well.

I don't know about others, but I wouldn't use reiserfs if you care about 
your data and aren't supplying redundancy above teh file system level 
(with glusterfs, for example).  I've seen multiple reports of how 
Reiserfs has a tendency to have unrecoverable errors in the file system 
when it gets sufficiently screwed up, basically necessitating a reformat 
of the partition.

>      Can we have a discussion on whether I'm heading in the right
> direction and what order things go in for the config files?

That depends on your goals.  What's important here, speed, redundancy, 
or a mix of both?

>      Also, any operational notes on running gluster on anything this
> big will be appreciated.


-Kevan Benson
-A-1 Networks

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