I concur. The Mylex seems to give excellent results under linux. I don't think the MegaRAID is hampered by a slow processor, though. This card seems to be a good performer under NT, so it may be in the linux driver. Mylex has (had? - I haven't checked for a while)a white paper benchmarking the ExtremeRAID to the MegaRAID. In some cases, the MegaRAID actually showed better performance numbers (no details were given as to how performance was measured). Mylex's main argument seemed to be that the ExtremeRAID had more usability features.
Also, I believe HP OEM's the MegaRAID for their Netservers. I doubt they would have done this if they couldn't get close to top-notch performance out of it.
Unless things have changed, the MegaRAID driver was written by the vendor (AMI), so their priorities are probably #1 - get it done quick (read cheap) and #2 make it stable to cut down on support calls. I doubt AMI sees enough market drive in the Linux arena to invest the development and testing to make the card perform at it's maximum capacity. I may just want to be able to put out press releases that say "Linux Support - Me, Too!"
Also, it may be interesting to point out that the Mylex driver for linux is *not* a SCSI driver. The author of the driver mentions that this was done for performance reasons. So I'm wondering if there are performance bottlenecks in the SCSI code. But that definately wouldn't jive with some of the awesome software RAID performance numbers I've seen posted to this list. A mystery!
Perhaps the author of the Mylex driver could comment.
-----Original Message-----
From: Brian D. Haymore [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 25, 1999 11:33 AM
To: [EMAIL PROTECTED]
Cc: linux-raid
Subject: Re: Hardware RAID
Matthew Clark wrote:
>
> Is there much info available on setting up Hardware RAID? Most info seems
> to be on Software (obvious reasons).. However - as you probably noticed, I'm
> having problems with my Hardware RAID and need to sort it ASAP..
>
> I was thinking about moving to kernel 2.2.13 but the parts of the kernel
> that may have an effect on MegaRAID Hardware performance (i.e. pci.*,
> megaraid.*, sym3c98xx.* etc) havn't been updated...
>
> Regards,
>
> Matthew Clark.
> --
> NetDespatch Ltd - The Internet Call Centre.
> http://www.netdespatch.com
I initailly purchased an AMI MegaRAID four or so months ago and saw
horible performance. I tried a DPT at that time as well before
setteling on a Mylex eXtremeRAID card. The AMI and DPT seem to both be
hindered by what I can only speculate as to slow of a sub processor,
their i960s. The Mylex uses a 233Mhz StrongARM processor. I see
numbers that are more in harmony with software raid with this card where
with the other two I saw performance that was more like a slow 5400 rpm
ide drive with little cache. As far as my tests showed, if you need
performance, software is the way to go. If you need the reliability of
hardware raid, then the Mylex card was the way to go.
I have numbers for all my tests that I could dig up if wanted.
--
Brian D. Haymore
University of Utah
Center for High Performance Computing
155 South 1452 East RM 405
Salt Lake City, Ut 84112-0190
Email: [EMAIL PROTECTED] - Phone: (801) 585-1755 - Fax: (801) 585-5366
