[Linux-cluster] GFS performance tuning

[Wendy Cheng]

Ross Vandegrift wrote:

>> 1. How to use "fast statfs".
>>     
>
> On a GFS2 filesystem, I see the following:
> [root at sensor02 ~]# gfs2_tool gettune /rrds
> ...
> statfs_slow = 0
> ...
>
> Does that indicate that my filesystem is already using this feature?
>   

The fast statfs patch was a *back* port from GFS2 to GFS1. In GFS2, fast 
statfs is the *default*.

>> 2. Disabling updatedb for GFS.
>> 3. More considerations about the Resource Group size and the
>>    new "bitfit" function.
>> 4. Designing your environment with the DLM in mind.
>>     
>
> Do you have any specific reading material you'd suggest on this topic?
> I suspect the interesting bits are related ot how GFS actually uses
> the DLM to lock filesystem metadata.  I've read some of Christine's
> DLM book, but there's not really anything related to GFS therein.
>   

I happen to have a new write-up about GFS locking. It, unfortunately, 
also interleaves with my current employer's disk block allocation policy 
(proprietary info). Note that GFS disk block handling has been 
piggy-backed on its glock logic. Would need sometime to clean it up for 
public reading. Stay tuned.

>   
>> 5. How to use "glock trimming".
>>     
>
> Is the glock trimming patch present in the cluster suite from RH5?
>   
For GFS1, yes.

For GFS2 ... it is a long story... I'll let other people comment it.

-- Wendy