[Linux-PowerEdge] PE 2950 PERC 5/i slow

Dale Dellutri daledellutri at gmail.com
Thu Mar 13 15:42:33 CDT 2014


On Thu, Mar 13, 2014 at 3:36 PM, Jake Smith <jsmith at argotec.com> wrote:
> Thanks Francis... wish that was it that but it's write back.
>
>
>
> We even bought a new 6/I and replaced the 5/i (now it matches the other
> 2950/6i system) and there was no change in performance.
>
> Everything except the CPU and memory chips are identical between them except
> one hits 140/MBs and the other only 20.

Just a thought: are the memory chips in the correct slots.  PowerEdge systems
generally need to have the chips arranged in a certain way to get the full
performance to memory.  Perhaps the memory bandwidth is the problem?

> Jake
>
> From: francis picabia [mailto:fpicabia at gmail.com]
> Sent: Thursday, March 13, 2014 3:26 PM
> To: Jake Smith; linux-poweredge at dell.com
> Subject: Re: [Linux-PowerEdge] PE 2950 PERC 5/i slow
>
>
>
>
>
> In case this helps...
>
>
>
> We went through troubles with 2950's and Perc 5.  They all had a battery
> which worked
>
> but was below a threshold.
>
>
>
> Here is how to test:
>
>
>
> omreport storage vdisk
>
>
>
> Look for "Write Policy".  If that line shows "Write Through", you are
> getting crappy
>
> performance because it won't use the memory cache on the controller.  The
> disks
>
> need to wait for another clock cycle before they can write again.  You must
> replace
>
> batteries on these before they completely fail.  I think it was something
> like below
>
> 30% rating the policy switches from Write Back (fast) to Write Through
> (slow).
>
> There is also a message like this from Open Manage in the logs:
>
>
>
> Jan 18 07:25:39 myserv Server Administrator: Storage Service EventID: 2335
> Controller event log: BBU disabled; changing WB virtual disks to WT:
> Controller 0 (PERC 5/i Integrated)
>
>
>
> It is nasty because the performance degradation does not come with any
> alarms
>
> or errors, just a quiet drop in performance.
>
>
>
>
>
>
>
>
>
> On Mon, Feb 24, 2014 at 1:13 PM, Jake Smith <jsmith at argotec.com> wrote:
>
> Hi All,
>
>
>
> I have two PE 2900's with identical 4x500GB Seagate SATA 7200 RPM drives in
> a RAID 10 on each.  Both running Ubuntu 12.04 Server x64 with the latest
> updates applied.
>
>
>
> Write test:
>
> dd if=/dev/zero of=/tmp/test count=5 bs=512M oflag=direct
>
>
>
> The PE with the PERC 5/i is getting about 20MB/s write speed regardless of
> write back/write through.
>
> The PE with the PERC 6/i is getting about 140MB/s with write through, 180
> with write back on the controller.
>
>
>
> Both have batteries and I've swapped them to rule out a failing (not
> reported) battery
>
> Swapped controller port 0 and 1 on the PERC 5 card.
>
> Pulled one drive at time and restested, pulled 1 and 2, pulled 1 and 3 - all
> no change.
>
> Tests all yield 18-20MB/s.
>
>
>
> Ran dstat - nothing using the drives
>
> Checked for any updated firmware - using the latest 5.2.2.0072.
>
> Driver version is 00.00.06.12-rc1
>
>
>
> Any ideas on what else to try or test?  I'm at a loss since I would expect
> something in the 70MB/s range from one drive alone and I'm not even in the
> ballpark.
>
>
>
> Jake
>
>
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>
>
>
>
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-- 
Dale Dellutri



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