[OT] Dell PERC raid cards. Was: request for comments

Jacob Coby jcoby at listingbook.com
Tue Apr 6 15:32:26 BST 2004


> As a matter of interest, would you have a link to anything that
> describes this issue? I've been using Dell PERC cards for *years*
> without any hint of a problem.

I thought I'd throw what I know into the mix:

Dell has 2 different types RAID chips: AACRAID and Megaraid(LSI).  They
repackage those two basic types into the PERC controllers [1].

>From what I understand, the Megaraid driver is less than reliable.  We have
three servers running on AACRAID (two 2450s and one 2650) that have been
plenty reliable -- not a single h/w failure, oops, or malfunction that could
be attributed to the dell hardware in 3 years.  Most (if not all) of the
major Linux distros provide support for the AACRAID, and it generally just
works.

We also have one 1750 with the PERC4/Di, based on the Megaraid chipset.  It
was very difficult to install any distro of Linux on.  Neither RedHat 7.3
nor Debian (stable/testing) had support in the kernel.  I had to track down
an install module before it would work [2].  Search google (groups), and
you'll find all sorts of stories like this, and some stories of array
corruption.  There are also some reports of the Megaraid chipset being slow.
I get pretty decent performance out of it [3].

We're running the 1750 as the primary production webserver, and haven't had
any real issues that I could attribute to the hardware.  It's only been up
41 days though.  I'll be avoiding any poweredge with the megaraid chipset in
the future.

--
-Jacob
Listingbook.com

1. http://linux.dell.com/storage.shtml
2. in addition to finding a module for the RAID controller, I had to grab
the network controller driver module from broadcomm as well -- there is no
support for it in redhat 7.3.
3. two runs of hdparm -t -T /dev/sda, a RAID 1 mirror

/dev/sda:
 Timing buffer-cache reads:   128 MB in  0.38 seconds =336.84 MB/sec
 Timing buffered disk reads:  64 MB in  3.46 seconds = 18.50 MB/sec

/dev/sda:
 Timing buffer-cache reads:   128 MB in  0.29 seconds =441.38 MB/sec
 Timing buffered disk reads:  64 MB in  0.45 seconds =142.22 MB/sec



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