[Linux-cluster] GFS performance.

[Ryan Golhar]

This brings up an interesting question for me....We can 6 machines that 
host a bunch of virtual machines.  I'd like to put the virtual machines 
on a shared SAN disk.  If one of the physical machines goes down, 
another one will take over and host a virtual machine.

Does it make sense to use GFS to manage the SAN then?  IF the 4x 
slowdown is there, then this may not be the way to go.

Jeff Sturm wrote:
>> -----Original Message-----
>> From: linux-cluster-bounces at redhat.com 
>> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Vikash 
>> Khatuwala
>> Sent: Monday, April 20, 2009 11:23 AM
>> To: linux-cluster at redhat.com
>> Subject: [Linux-cluster] GFS performance.
>>
>> OS : CentOS 5.2
>> FS : GFS
> 
> Can you easily install CentOS 5.3 and GFS2?  GFS2 claims to have some
> performance improvements over GFS1.
> 
>> Now I need to make a decision to go with GFS or not, clearly 
>> at 4 times less performance we cannot afford it, also it 
>> doesn't sound right so would like to find out whats wrong.
> 
> Be careful with benchmarks, as they often do not give you a good
> indication of real-world performance.
> 
> Are you more concerned with latency or throughput?  Any single read will
> almost certainly take longer to complete over GFS than EXT3.  There's
> simply more overhead involved with any cluster filesystem.  However,
> that's not to say you're limited as to how many reads you can execute in
> parallel.  So the overall number of reads you can perform in a given
> time interval may not be 4x at all (are you running a parallel
> benchmark?)
> 
> Jeff
> 
> 
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