Re: [Rdo-list] cinder speed (slow nova?)

-----Original Message----- From: rdo-list-bounces(a)redhat.com [mailto:rdo-list-bounces@redhat.com] On Behalf Of Cristian Falcas Sent: Tuesday, December 23, 2014 1:30 AM To: Dmitry Makovey Cc: rdo-list Subject: Re: [Rdo-list] cinder speed (slow nova?) Nova has as default cache for disks a very safe value (I think file=directsync or writethrough). Try to change it to writeback: disk_cachemodes="file=writeback"

On Tue, Dec 23, 2014 at 1:13 AM, Dmitry Makovey <dmitry(a)athabascau.ca&gt; wrote: > note that all of below applies when cirros used as guest... > > On 12/22/2014 04:10 PM, Dmitry Makovey wrote: >> Hi everybody, >> >> using RDO IceHouse packages I've set up an infrastructure atop of >> RHEL6.6 and am seeing a very unpleasant performance for the storage. >> >> I've done some testing and here's what I get from the same storage: >> but different access points: >> >> cinder-volume # dd if=/dev/zero of=baloon bs=1048576 count=200 >> 200+0 records in >> 200+0 records out >> 209715200 bytes (210 MB) copied, 0.162997 s, 1.3 GB/s >> >> nova-compute # dd if=/dev/zero of=baloon bs=1048576 count=200 >> 200+0 records in >> 200+0 records out >> 209715200 bytes (210 MB) copied, 0.167905 s, 1.2 GB/s >> >> instance # dd if=/dev/zero of=baloon bs=1048576 count=200 >> 200+0 records in >> 200+0 records out >> 209715200 bytes (210 MB) copied, 10.064 s, 20.8 MB/s >> >> A bit of explanation: in above scenario I have created LV on >> cinder-node, then mounted it locally and ran command for >> "cinder-volume". Created an iSCSI target, mounted it on nova-compute, >> and ran command there. Then, via cinder created storage volume, >> booted the OS off it, and ran test from within it... Results are just >> miserable. going from 1.2G/s down to 20M/s seems to be a big >> degradation. What should I look for? I have also tried running the >> same command within our RHEL KVM instance and got great performance. >> >> I have checked under /var/lib/nova/instances/* and libvirt.xml seems >> to indicate that virtio is being employed: >> >> <disk type="block" device="disk"> >> <driver name="qemu" type="raw" cache="none"/> >> <source >> dev="/dev/disk/by-path/ip-192.168.46.18:3260-iscsi-iqn.2010- 10.org.openstack:volume-955b25eb-bb48-43c3-a14d-222c9e8c7019-lun-1"/> >> <target bus="virtio" dev="vda"/> >> <serial>955b25eb-bb48-43c3-a14d-222c9e8c7019</serial> >> </disk> >> >> guest used - is rhel-guest-image-6.6-20140926.0.x86_64.qcow2 >> downloaded off RH site. > > > > -- > Dmitry Makovey > Web Systems Administrator > Athabasca University > (780) 675-6245 > --- > Confidence is what you have before you understand the problem > Woody Allen > > When in trouble when in doubt run in circles scream and shout > http://www.wordwizard.com/phpbb3/viewtopic.php?f=16&t=19330 > > > _______________________________________________ > Rdo-list mailing list > Rdo-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/rdo-list > _______________________________________________ Rdo-list mailing list Rdo-list(a)redhat.com https://www.redhat.com/mailman/listinfo/rdo-list