MD1000 recommendations?

[Ryan Bair]

I've been really happy with our MD1000's. I would recommend them to
anyone looking for DAS.

To answer Matthias's question as well as a word of warning to you,
cranking up the readahead on the block device device really works
wonders for performance. I have mine set at 8K and it works out well.
I also have fairly large files so YMMV. I have also found that using
the deadline io scheduler gives much better responsiveness under load
than the default CFQ.

--Ryan

2008/3/24 mcclnx mcc <mcclnx at yahoo.com.tw>:
> I followed the document and setup MD1000 and highest performance I got is
> 86MB/sec.
>
> Configuratio:
>
> DELL 6800 with two dual core CPU.
> 32 GB RAM
> one PERC 5/E controller
> Redhat AS 3.9
>
> MD1000 configure Raid10 (disk 0 to 13)
> stripe size 128kb
> read ahead and cache enable.
>
> /sbin/blockdev --setra 64 /dev/sdf
>
> ============================
> hdparm -t /dev/sdf1
>
> /dev/sdf1:
>  Timing buffered disk reads:  246 MB in  3.07 seconds =  80.13 MB/sec
>
> any suggestion to improve it?
>
> Thanks.
>
> Matthias Saou
> <thias at spam.spam.spam.spam.spam.spam.spam.egg.and.spam.freshrpms.net> 說：
>
>  Stephan Jansen wrote :
>
> > We are likely going to purchase a small cluster of Dell
> > PowerEdge 1950III machines. We're looking for a good
> > RAID box to attach to the head node of the cluster. We
> > were thinking of getting an Apple Xserve RAID but now
> > that Apple is abandoning that product we're looking for
> > alternatives. So, the question is, what do people think
> > of the MD1000? So far as I am aware, the RAID box does not
> > need to be blazingly fast. We just want something that
> > will work with Linux (OpenSuSE 10.3 probably), is "reasonably"
> > priced, has good monitoring and no known issues.
> >
> > What do people think of the MD1000? Any issues? Are there
> > any other RAID boxes you would recommend?
>
> It's a device with a very decent price/capacity ratio. It does need
> some tweaking to get acceptable performance, though. I've written
> something regarding my discoveries here :
> http://thias.marmotte.net/archives/2008/01/05/Dell-PERC5E-and-MD1000-performance-tweaks.html
>
> As for the PERC5/E (capital "E" as in "External", not "e" as in
> "PCI-express" ;-)) that usually comes with it, it's not that bad once
> tuned properly. I can monitor it just fine with MegaCLI, since the
> servers have their internal RAID on an integrated SAS6/iR, which uses a
> different chip and monitoring tool, FWIW.
>
> Matthias
>
> --
> Clean custom Red Hat Linux rpm packages : http://freshrpms.net/
> Fedora release 8 (Werewolf) - Linux kernel 2.6.23.15-137.fc8
> Load : 0.43 0.64 0.36
>
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