[Linux-cluster] GFS performance.

[Vikash Khatuwala]

Hi Jeff,

I tried that but I could not mount the partition anymore.

# gfs_tool sb /dev/mapper/cvg-vz01 proto no_lock
You shouldn't change any of these values if the filesystem is mounted.

Are you sure? [y/n] y

current lock protocol name = "lock_dlm"
new lock protocol name = "no_lock"
Done
# mount /vz
/sbin/mount.gfs: error mounting /dev/mapper/cvg-vz01 on /vz: No such 
file or directory

After I change it back to lock_dlm, I can mount the volume as usual.

Is there anything else I need to do?

Regards,
Vikash.

At 03:56 AM 26-04-09, Jeff Sturm wrote:
>Yes, and yes.  Use the "gfs_tool sb <device> proto no_lock" command on
>an unmounted filesystem, and remount.  (Obviously, you cannot mount the
>fs on more than one node after you do this.)
>
>Jeff
>
> > -----Original Message-----
> > From: linux-cluster-bounces at redhat.com
> > [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Vikash
> > Khatuwala
> > Sent: Saturday, April 25, 2009 4:26 AM
> > To: linux clustering
> > Subject: RE: [Linux-cluster] GFS performance.
> >
> > Hi,
> >
> > Can I downgrade the lock manage from lock_dlm to no_lock? Do
> > I need to un-mount the gfs partition before changing? I want
> > to see if it makes any performance improvements.
> >
> > Thanks,
> > Vikash.
> >
> >
> > At 11:18 AM 21-04-09, Vikash Khatuwala wrote:
> > >Hi,
> > >
> > >I am using Virtuozzo OS visualization which does not have a
> > single file
> > >for the entire VM's filesystem. All VMs are simply
> > sub-directories and
> > >OS files are stored in a common templates directory which is
> > sym linked
> > >to back to the VM's directory, so if an OS file is changed
> > inside the
> > >VM then the symlink breaks and a new file is put in the VM's private
> > >directory. I cant use GFS2 because it is not supported by Virtuozzo.
> > >All VMs are simply running web/db/ftp.
> > >
> > >So this basically means that there are a lot of symbolic
> > links (small
> > >files). The GFS has a block size of 4K so I also chose 4K as
> > my block
> > >size for my performance testing to asses the worst case
> > scenario. If I
> > >change the block size to 256K then the performance
> > difference between
> > >ext3 and GFS are minimal. Also when I migrate the VM out
> > from GFS(RAID5
> > >SAS 15K) to ext3(single disk SATA), there is a significant
> > noticeable
> > >performance gain!
> > >
> > >Below tests are on the same disk set (5 disk RAID5 SAS 15K) with 2
> > >partitions, GFS and ext3.
> > >Results at 4K random reads:
> > >GFS : about 1500K/s
> > >ext3 : about 7000K/s
> > >
> > >Results at 256K random reads:
> > >GFS : about 45000K/s
> > >ext3 : about 50000K/s
> > >
> > >Results at 256K sequential reads:
> > >GFS : over 110,000K/s (my single GB NIC maxes out)
> > >ext3 : over 110,000K/s (my single GB NIC maxes out)
> > >
> > >fio test file as below only rw and blocksize were changed for the 3
> > >different scenarios above.
> > >[random-read1]
> > >rw=randread
> > >size=10240m
> > >directory=/vz/tmp
> > >ioengine=libaio
> > >iodepth=16
> > >direct=1
> > >invalidate=1
> > >blocksize=4k
> > >
> > >[random-read2]
> > >rw=randread
> > >size=10240m
> > >directory=/vz/tmp
> > >ioengine=libaio
> > >iodepth=16
> > >direct=1
> > >invalidate=1
> > >blocksize=4k
> > >
> > >Thanks,
> > >Vikash.
> > >
> > >
> > >At 01:00 AM 21-04-09, 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
> > >>
> > >>
> > >>--
> > >>Linux-cluster mailing list
> > >>Linux-cluster at redhat.com
> > >>https://www.redhat.com/mailman/listinfo/linux-cluster
> >
> > --
> > Linux-cluster mailing list
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> >
> >
>
>
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