[Gluster-devel] Full bore.
Chris Johnson
johnson at nmr.mgh.harvard.edu
Thu Nov 15 17:56:05 UTC 2007
On Thu, 15 Nov 2007, Kevan Benson wrote:
> 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 might if I get another one.
>
>> 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
> specified).
>
> 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.
About what I thought but the wiki sounded otherwise.
>
>> 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.
Huh. Now that's interesting. We've been running our mail server
off Reiserfs for a few years now and never an issue. It's servived
power outs and dropped drives. We're using software RAID on it.
>
>> 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?
>
Both of course. Are the mutually exclusive? Please, I know
they can be to some extent. I'm talking about the real world,
whatever that is. I need to get the performance up,
redundancy/failover would be be real good too. NFS has a few problems
with that.
>> Also, any operational notes on running gluster on anything this
>> big will be appreciated.
>
>
> --
>
> -Kevan Benson
> -A-1 Networks
>
>
>
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Chris Johnson |Internet: johnson at nmr.mgh.harvard.edu
Systems Administrator |Web: http://www.nmr.mgh.harvard.edu/~johnson
NMR Center |Voice: 617.726.0949
Mass. General Hospital |FAX: 617.726.7422
149 (2301) 13th Street |Do not meddle in the affairs of wizards, for
Charlestown, MA., 02129 USA |they are subtle and quick to anger.
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