RAID controller question...

[Stanley, Jeremy]

The MegaRAID spec sheets claimed to have a vt100 compatible serial
console port for access to all the BIOS level features without
disturbing the host system, if I remember correctly...
-------------------------*-------------------------
Jeremy J. Stanley
Information Systems Administrator
Trend Community Mental Health Services


> ----------
> From: 	Eric Billings[SMTP:billings@helix.nih.gov]
> Sent: 	Monday, September 07, 1998 3:29 PM
> To: 	Stanley, Jeremy
> Cc: 	'Beowulf Cluster Mailing List'; 'Extreme Linux Mailing List'
> Subject: 	Re: RAID controller question...
> 
> > which I think will work, but can't find pricing on either and am not
> > sure if LINUX drivers exist for each.  The controllers are:
> > 
> > 	AMI MegaRAID® Ultra2/5 (Series 438)
> > 
> We are currently running the AMI MegaRAID UltraGT under Linux 2.0.31
> with
> a vendor-supplied driver.  It is configured as RAID-5 with 8 18GB
> drives
> spread across the 3 channels of the controller.  It has 128MB on-board
> cache.  Performance with this is fine - not great.
> 
> For burst writes and reads we are measuring 20-30MB/s for files < 50K
> that
> are cacheable.  Sustained writes to disk are about 2.2MB/s with 8
> disks in
> a single logical volume and data-striping enabled for files > 1GB.
> 
> We are currently testing data recovery.  This takes a while because
> loading the disk with >100GB of data takes more than 12 hours.
> 
> CAVEAT EMPTOR: Hardware supported RAID requires that you can get to
> the 
> controller's code to rebuild a lost disk.  This means that you must
> take 
> the system down and reboot to get to the PCI controller during the
> boot
> sequence.  This eliminates advantages such as hot-swap and keeping the
> 
> host node accessible during the rebuild process.  At least so far...
> 
> - Eric
> 
> ----------------------------------------------------------------------
> 
> Dr. Eric Billings                                Voice: (301) 496-6520
> Laboratory of Biophysical Chemistry               FAX:  (301) 496-2172
> National Institutes of Health            email: billings@helix.nih.gov
> LoBoS: Lots of Boxes on Shelves              http://www.lobos.nih.gov/
> ----------------------------------------------------------------------
> 
>