[K12OSN] Onboard RAID or Software RAID

[Fabio Milano]

I have used both Hardware RAID (real hardware raid) and Software RAID
(OS raid). While Hardware RAID controllers will give you a better
performance their price is very high. I would recommend using the OS
RAID, its robust and I have even tested it by simulating a
powerfailure while the drives were actively working. The OS RAID staid
intact and no data was lost (ext3 file system).

Once your system is up and running use the following command to test
your drive speed

#hdparm -Tt /dev/md0

Timing buffered disk reads:  132 MB in  3.03 seconds =  43.54 MB/sec
Is what I get with a VIA onboard SATA controller.

With SCSI drives I usually get around 90.00MB/sec +




On 1/17/07, Robert Arkiletian <robark at gmail.com> wrote:
> On 1/17/07, Dan Young <dyoung at mesd.k12.or.us> wrote:
> > Krsnendu dasa wrote:
> > > I am just not sure whether to use the RAID on the motherboard or
> > > software RAID.
> > > I know addon RAID cards (e.g . 3ware) have been recommended, but for now
> > > I just want to use what I have.
> > >
> > > I have a motherboard with VIA VT8237 SATA RAID BIOS Ver 2.31
> > >
> > > In addition how do I monitor the disks. Basically, if one disk fails,
> > > how will I know?
> > >
> > > What are the pluses and minuses of going with either option.
> >
> > http://linuxmafia.com/faq/Hardware/sata.html#via8237
> > It's fakeraid, i.e. it relies on software drivers rather than hardware
> > to provide RAID.
>
> the via vt8237 doesn't even have NCQ (native command queing). But it
> should do fine in a software raid using mdadm. Software raid 1 using
> mdadm is robust.
>
> >
> > The dmraid driver might work; looks like work in progress.
> > http://people.redhat.com/~heinzm/sw/dmraid/readme
> > http://fedoraproject.org/wiki/DmraidStatus
> >
> > VIA apparently has proprietary RAID drivers, I tried to look deeper on
> > their page but it made my eyes bleed:
> > http://www.viaarena.com
> >
> > Software RAID (the md driver) works great. "cat /proc/mdstat" to see
> > status; I think the mdadm tools come with a cron job to test the arrays
> > and send you mail if the array degrades. Probably a winner if you want
> > your stuff to actually work.
> >
>
> I didn't know mdadm could do this. This is how I get my system to
> notify me of a failure.
>
> 1) edit /etc/mail/sendmail.mc find the smart_host line and set it to
> your mail server
> ex. smtp.mymailserver.net
>
> 2) again editing /etc/mail/sendmail.mc find masquarade_as and set your
> mail server domain
> ex. mymailserver.net
>
> 3) again editing /etc/mail/sendmail.mc enable feature(masquarade_envelope)
>
> then issue this command as root on one line
>
> m4  /usr/share/sendmail-cf/m4/cf.m4  /etc/mail/sendmail.mc  >
> /etc/mail/sendmail.cf
>
> then
>
> service sendmail restart
>
> then try this
>
> echo "raid array dead  ." | mail -s "north server" someemail at somewhere.com
>
> if it works then stick this into a cron one liner like this
>
> 3 21 * * *     grep  _  /proc/mdstat | grep -v read_ahead ; if [ $?
> -eq 0 ]; then echo "raid array failure  ." | mail -s "my k12ltsp
> server" someemail at somewhere.com
>
> cool huh?!? BTW don't forget the "." in the end of the echo text
> Beware: I haven't had a failure yet so I am not 100% sure it works. :)
>
> --
> Robert Arkiletian
> Eric Hamber Secondary, Vancouver, Canada
> Fl_TeacherTool http://www3.telus.net/public/robark/Fl_TeacherTool/
> C++ GUI tutorial http://www3.telus.net/public/robark/
>
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