DELL|EMC CX300 + PowerEdge 2850 + RHEL ES 3.0 U7 + REDHAT CLUSTERMANAGER SUITE 3.0

Irwan Hadi ihblist at gmail.com
Wed Apr 26 01:05:48 CDT 2006


Last year I had a performance issue with a Dell PE2800 with PERC 4e/di
running Microsoft Windows Server 2003 and has Gold support for our
Exchange 2003 server. It took around 2 months to get resolved, with
*NO* effort at all from Dell gold support. Took me around 200 hours
personal time during this ordeal, mainly friday and saturday night.
In the end my conclusion was a Dell PERC can not handle a RAID 5
volume with bigger than 4 X 146 GB hard drives or the random read
performance will be so poor that a tortoise is still faster.

The problem is not mainly with Dell though. It is with the
manufacturer of the PERC controller (LSI Logic in this case), as I
tried their MegaRaid 320-4X (rebranded as PERC 4/QC) which is supposed
to be LSI's top of the line product, and it performs even more poor.

Anyway, back to this EMC CX300 thing which supposedly to have
relatively the same performance with NetApp FAS270, the sequential
write seems to be correct. Our NetApp FAS270 can do sequential write
at about 60 MB/s before the processor is maxed. The thing that used up
the processor is mainly the parity calculation (either RAID 5 for EMC,
or RAID 4 / RAID DP with NetApp). Of course snapshot with NetApp only
takes < 1 second to finish, and doesn't need a special volume (BCV)
unlike EMC.

In any case, I strongly believe that every storage system either it is
from big vendors such as EMC, NetApp, Hitachi HDS, HP EVA, or small
vendors such as Equallogic, leftHand, bluearc, pillar data, etc. have
their own quirks, and also strengths. Problem it is, is to find and
work around the quirks.

So far we've been very happy and satisfied with NetApp, though it
costs about an arm (not yet an arm and a leg like EMC). We are not
that happy with LSI (due to their MegaRAID / PERC controller). We are
not quite happy with EMC as we've heard quite a few horror stories
with EMC.


On 4/25/06, Rankin, Kent <RankinK at orau.gov> wrote:
> Expect terrible performance, and even worse support.
>
> My organization is nine weeks into a support call regarding performance problems on a pair of CX300's.  When we initiate a snapshot, we can't get more than 4-5MBps of sustained write performance out of a 3-tray CX300.  When everything is just dandy, our processors max out when any combination of LUN's is writing ~55MBps.
>
> The support situation has been an absolute nightmare, as Dell's sales and support staff have been doing their best to discredit anything that we say, rather than to address the problem at hand.  For instance, we bought one tray of SATA disks for a Windows fileserver, and can't get more than 28MBps of sustained write to 14 500GB disks in RAID 5 configuration.  They sold it for a Windows fileserver, yet claim that Windows file copies are not an appropriate way to claim whether or not it functions to spec.  *sigh*  I won't even get into the fact that they claim that another tray of SATA disks are performing excellently for a pre tape (2x LTO3 tape drive) disk backup solution, even though they can't break 30MBps.
>
> In my experience, so far, the best systems to look at are the Engenio devices sold by Storagetek, IBM, Sun, SGI, etc.  Netapp also has devices that will grossly outperform these.  These CX300's have nice management software, but are absolutely the worst performing devices that I've ever seen.
>
> Not to mention that they sell them with 2GB of cache, and then use about 1100MB of that to run Windows XP Embedded on the controllers.  So you wind up with a giant, gaping security hole (unpatched Windows), plus under half of the cache that they advertise.
>
>
> --
> Kent Rankin
> UNIX Systems Administrator
> Information Systems Department
> Oak Ridge Associated Universities
>
> ________________________________________
> From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-bounces at dell.com]
> Sent: Tuesday, April 25, 2006 4:50 AM
> To: linux-poweredge at dell.com
> Subject: DELL|EMC CX300 + PowerEdge 2850 + RHEL ES 3.0 U7 + REDHAT CLUSTERMANAGER SUITE 3.0
>
> Hello here DELL people,
>
> Good day!
>
> I just want to ask ifthere is any white paper or maybe a linkon DELL that has implemented this configuration. I wish to setup a 2 DELLPowerEdge 2850 on aHA linux cluster using Redhat Cluster Manager Suite 3.0 that I can use as a reference.
>
> Please help
>
> ahmadz
>
>
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