On Thu, Feb 26, 2009 at 03:38:49PM -0500, Lennart Sorensen wrote:
> On Thu, Feb 26, 2009 at 11:41:03AM +1100, Alex Samad wrote:
> > This begs the question why did you pick hardware raid over software raid
> 
> You can boot from it no matter what (software raid can require interesting
> tweaks to the boot loader setup to make it work).

my rule of thumb is to always have atleast 2 partitions on the first 2
drives (3 if I have them), for a raid1 /boot and a raid1 /. the rest of
the space is put into a raid device then into lvm.  That gets rid of the
interesting tweaks.


> 
> Recovery can be transparent to the OS and be as simple as swapping out
> the drive that failed.

true

> 
> You get nice hotswap bay LED control to show which drive has failed
> (I imagine software could do this too, but I have never seen that
> happen yet.)

true

> 
> > I have been a long supporter of software raid, but I find myself leaning
> > towards a HP smart array 400 and using hardware raid (looking at 10
> > disks in raid6).
> > 
> > My current thoughts are why should I have 10 channels (4 of them come
> > from 1 pcix card) when I could have 1 channel to the smart array. there
> > seem to be a few cciss utilities for me to track the array 
> > 
> > 
> > I am waying this up against the ability to easily manage the array and
> > do upgrade and change disk and monitor the individual disks
> 
> Some hardware raids have good support for monitoring under linux.
> Some do not.  Having monitoring is quite important.

is that monitoring of the raid drives or the actual drives underneath, I
like having smartctl to give me access to the actual drive health

> 
> The biggest advantage to software raid is that it is hardware independant.
> You can move all the disks to another controller type on another system,
> and linux's software raid will still work.  Hardware raid setups are
> often very specific to one controller type so recovery from a controller
> failure can be tricky if you don't have access to spares.

I have gone through a few cycles of changing the underlying drive sizes,
ie a 3 disk raid5 made up of 3 x 500Gb and replacing in line with 3 x
TB.  pop 1 disk replace with 1 TB once it has settled you can do an
online expansion.  Not sure if you can do that on a HW raid.

> 
> -- 
> Len Sorensen
> 
> 
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-- 
"I suspect that had my dad not been president, he'd be asking the same 
questions: How'd your meeting go with so-and-so? ... How did you feel when you 
stood up in front of the people for the State of the Union Address--state of 
the budget address, whatever you call it."

        - George W. Bush
03/09/2001
in an interview with the Washington Post

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