Brock Palen
2010-Dec-14 20:33 UTC
[Lustre-discuss] testing block device performance while lustre is running
Is there a safe way to test block device read performance while lustre is using the device? Example a type of read only access to the device to check that it is performing correctly? Or is this a bad idea? Brock Palen www.umich.edu/~brockp Center for Advanced Computing brockp at umich.edu (734)936-1985
Joe Landman
2010-Dec-14 20:37 UTC
[Lustre-discuss] testing block device performance while lustre is running
On 12/14/2010 03:33 PM, Brock Palen wrote:> Is there a safe way to test block device read performance while > lustre is using the device? Example a type of read only access to > the device to check that it is performing correctly?Brock We allocate a small aligned partition before the Lustre OST partition for read and write testing. If you don''t have this, you might be able to do read testing. The latter you would need to do with dd on the raw device dd if=/dev/sdXP of=/dev/null bs=128k count=Z where X is the drive, P is the partition number (if any), and Z is the number of 128k blocks you want to read. Don''t mix up if and of arguments (e.g. this can be a dangerous command with a minor typo)> > Or is this a bad idea?It will impact OST performance if you wind up increasing resource contention. Regards, Joe> > Brock Palen www.umich.edu/~brockp Center for Advanced Computing > brockp at umich.edu (734)936-1985 > > > > _______________________________________________ Lustre-discuss > mailing list Lustre-discuss at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-discuss-- Joseph Landman, Ph.D Founder and CEO Scalable Informatics Inc. email: landman at scalableinformatics.com web : http://scalableinformatics.com http://scalableinformatics.com/sicluster phone: +1 734 786 8423 x121 fax : +1 866 888 3112 cell : +1 734 612 4615
Brock Palen
2010-Dec-14 20:40 UTC
[Lustre-discuss] testing block device performance while lustre is running
On Dec 14, 2010, at 3:37 PM, Joe Landman wrote:> On 12/14/2010 03:33 PM, Brock Palen wrote: >> Is there a safe way to test block device read performance while >> lustre is using the device? Example a type of read only access to >> the device to check that it is performing correctly? > > Brock > > We allocate a small aligned partition before the Lustre OST partition > for read and write testing. If you don''t have this, you might be able > to do read testing. The latter you would need to do with dd on the raw > device > > dd if=/dev/sdXP of=/dev/null bs=128k count=ZThis is what I thought I could try, we have just seen a degration in performance on our OST''s and trying to track down why. Thanks> > where X is the drive, P is the partition number (if any), and Z is the > number of 128k blocks you want to read. Don''t mix up if and of > arguments (e.g. this can be a dangerous command with a minor typo) > >> >> Or is this a bad idea? > > It will impact OST performance if you wind up increasing resource > contention.Figured Thanks> > Regards, > > Joe > >> >> Brock Palen www.umich.edu/~brockp Center for Advanced Computing >> brockp at umich.edu (734)936-1985 >> >> >> >> _______________________________________________ Lustre-discuss >> mailing list Lustre-discuss at lists.lustre.org >> http://lists.lustre.org/mailman/listinfo/lustre-discuss > > > -- > Joseph Landman, Ph.D > Founder and CEO > Scalable Informatics Inc. > email: landman at scalableinformatics.com > web : http://scalableinformatics.com > http://scalableinformatics.com/sicluster > phone: +1 734 786 8423 x121 > fax : +1 866 888 3112 > cell : +1 734 612 4615 > _______________________________________________ > Lustre-discuss mailing list > Lustre-discuss at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-discuss > >