Re: slow I/O on v7000 SAN
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On the Red Hat and IBM ticket mention - I wasn't really complaining about either support. They have been pretty responsive. Just we are not finding the underlying cause. Red Hat support is pretty good - I have seen much worse. I didn't mean to come off annoyed by RH tech support. I really cant see where the issue is. At first I thought it might be a fencing issue, or a gfs2 tuning issue (plocks, etc). Recently I started looking at it from the SAN side - wondering if somethig was amiss there. On 11/16/2011 12:07 PM, Michael Bubb wrote: > > > On 11/16/2011 11:54 AM, Steven Whitehouse wrote: >> Hi, >> >> On Wed, 2011-11-16 at 11:42 -0500, Michael Bubb wrote: >>> Hello - >>> >>> We are experiencing extreme I/O slowness on a gfs2 volume on a SAN. >>> >>> We have a: >>> >>> Netezza TF24 >>> IBM V7000 SAN >>> IBM Bladecenter with 3 HS22 blades >>> Stand alone HP DL380 G7 server >>> >>> >>> The 3 blades and the HP DL380 are clustered using RHEL 6.1 and >>> clustersuite 5.5. >>> >> You should ask the Red Hat support team about this, as they should be >> able to help. > > I assumed that this would be assumed. I have had a ticket in for a > while. The ticket is not going anywhere. I have sent sosrepts, etc... I > also have aticket in with IBM regarding the SAN. After a day they came > back and told me "Yes, you have I/O slownesss...." > > So I thought I would hit the community and see if this rings a bell with > anyone else. >> >>> We have 2 clustered volumes on different storage pools (one has 10k >>> drives the other 7.2k). >>> >>> We have an internal test that reads a large file (950G) using fopen and >>> memmap. On a standalone server in a datacenter (Ubuntu Raid 5 10k disks) >>> the tests take approximately 75seconds to run. >>> >>> On the blades the test takes 300 - 350 seconds. >>> >>> I have been looking at the cluster conf; any gfs tuning I can find. I am >>> not really sure what I should post here? >>> >>> yrs >>> >>> Michael >>> >> So it is a streaming data test. Are you running it on all three nodes at >> the same time or just one when you get the 300 seconds times? Did you >> mount with noatime,nodiratime set? > > We tested first all nodes, then one node. There is amazing consistency > here. He have run this test about 10 times in different scenarios and it > is always about 5 times slower than the Ubuntu SATA Raid5 volume. > >> >> Are the drives you are using just a straight linear lvm volume from a >> JBOD effectively? > THey are RAID6 mdisks on the SAN organized into storage pools. THe > volumes are created on top of this. >> >> Steve. >> >> >> -- >> Linux-cluster mailing list >> Linux-cluster@xxxxxxxxxx >> https://www.redhat.com/mailman/listinfo/linux-cluster > > > > -- > Linux-cluster mailing list > Linux-cluster@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-cluster -- Michael Bubb System Administrator .................................................. T: +1.646.380-2738 | C: +1.646.783.8769 mbubb@xxxxxxxxxxxxxx | michael.bubb@xxxxxxxxx .................................................. Collective | collective.com | Twitter: @collectivesays 99 Park Ave. 5th Floor | New York, NY 10016 | +1.888.460.9513 ..................................................
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