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RE: [Linux-cluster] GFS performance.



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 redhat com
> [mailto:linux-cluster-bounces 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 redhat com
> >> > [mailto:linux-cluster-bounces redhat com] On Behalf Of Vikash
> >> > Khatuwala
> >> > Sent: Monday, April 20, 2009 11:23 AM
> >> > To: linux-cluster 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 redhat com
> >>https://www.redhat.com/mailman/listinfo/linux-cluster
>
> --
> Linux-cluster mailing list
> Linux-cluster redhat com
> https://www.redhat.com/mailman/listinfo/linux-cluster
>
>


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