[Bassetlug mailing] Setting up RAID

[Rev Mark Pengelly]

Was Philip's discussion all relating to mdadm? We use that on the
crossings' server. it is of course 'software raid' not to be confused
with a hardware raid controller.

Occasionally we have had glitches with our raid 1 setup, ie a disk drops
out of the raid and then md commands are used to add it back in. So far
it has always done so, although sometimes we have had to do a cold
reboot of the machine.

Hardware raid is preferable if available. Most compaq servers raid
hardware is supported in linux and can usually see a partition as a boot
device when installing, once the array is setup using the proprietary
software (SmartStart in the case of compaq).

I have a pci hardware raid card on my main ubuntu machine, but never
really got it working properly.

Many modern motherboards with sata raid are actually only using
(windows) software to create the raid, it's not full proper hardware
raid (I think).

if anyone wants to play with raid I have 2 x compaq 1500 servers, one
with 5 drives, one with 3 drives in it. I had redhat 6 running merrily
on it about 5 years ago, I also have a scsi attached array case with
another 7 drives in (only 2.1gb per drive). I've been meaning to clear
this out for months, free to a good home! only catch - you need to have
ear defenders on when all the drives start up! i ran mine in the
garage!! Perhaps I'll bring it to bassetLUG show how to set it up and
then someone else could take it home!?

Sounds good Philip, sorry I missed it! Raid is definately cool, what
about raid 5?! my favourite!

Mark



On Thu, 2009-03-19 at 13:55 +0000, MJ.Wells wrote:

> Good to see 'old' and 'new' members at the meeting last evening where Philip
> gave us a very informative demonstration of setting up RAID in Ubuntu.
> 
> Philip told us that he had occasionally seen problems when he set up some
> systems which he felt were due to not having identical drives in the array
> as is recommended. 
> 
> Philip then showed us that  setting up the RAID in the BIOS causes Linux to
> be unable to find the boot loader so that the most expensive of equipment
> just loops at boot as it could save me much time in the future. It seems
> that the boot partition has to be excluded from RAID.
> 
> Philip went on to explain the difference between RAID 0 (striped) and RAID 1
> (mirrored) along with the more complex RAID 10 (1+0) which combines both.
> After a detailed setup of the partitions using the hardware RAID which led
> to the failure to boot, Philip showed us the process of setting up the
> drives in the Ubuntu Server install. Finally we looked at leaving the setup
> of the RAID until Ubuntu had been fully loaded on some of the disks.
> 
> Unfortunately, even though we extended our evening until well past 10pm as
> we were enjoying the demonstration so much, we had to leave the full use of
> mdadm until another time.
> 
> I have not encountered this technology before and have learned a lot. Thanks
> Philip for a very informative and useful demonstration. Now ... I wonder
> where can I lay my hands on four unwanted 500Gb-ish drives so that I can try
> it all for myself?
> 
> Martin
> 
> 
> 
> 
> _______________________________________________
> Bassetlug mailing list
> Bassetlug at mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bassetlug
>