RAID Controllers and Linux: Ugh!

[Warren Luebkeman]

I have setup a software RAID once in Debian, however I was under the 
impression that hardware raid was the way to go because the recovery is 
better.  I'm using RAID 1, so I need to make sure the system doesn't go down 
if a hard drive crashes, and that it boots properly if a hard drive crashes.

That being said, I wouldn't have a problem using an OS supported software raid 
if it was as robust as hardware RAID.  It would certainly save a few bucks on 
the controller.

On Friday 29 June 2007 5:06 pm, Tom Buskey wrote:
> On 6/29/07, Warren Luebkeman <warren at resara.com> wrote:
> > Since we are on the subject of servers, I am now dealing with an issue
> > that I
> > always face when using a new server configuration:  Is the RAID Card
> > supported in Linux?  I usually like to go with Adaptec RAID cards because
> > they provide Linux driver sources so we can compile the driver ourselves.
>
>  ....
>
> I guess this is more of a frustrated rant rather than a question.  It looks
>
> > like I will have to use the Adaptec card, which I have no problem with,
> > except that its about $400.  Just seems silly (and incredibly annoying)
> > to me.
>
> I used to be all for hardware raid but my thinking has changed over the
> years.  I prefer software RAID that the OS supports w/o extra drivers
>
> I saw someone reconfigure a hardware RAID on Solaris and make a mistake in
> fstab.  Solaris was installed on the RAID and wouldn't boot.  The install
> CD would boot, but it didn't have the drivers for the RAID so he couldn't
> mount /etc to edit fstab.  That mistake cost him a few hours to fix.
>
> Hardware RAID has a dedicated CPU to handle the XORing for RAID 5.  That
> was important when you had a 486.  Now you have a multicore multi GHz cpu
> with extra capacity.  Doing an extra computation will not add much
> overhead.
>
> What if the RAID card dies?  Can you get a replacement that can read the
> RAID disks you have now?
>
> Sun's 3510FC RAID box had a firmware bug that would make disks disappear.
> It happened to 2 drives in a RAID 5 configuration I had.  I had a corrupted
> RAID and lost the data.  There have been 2 patches since then.
>
> I'm now using ZFS on Solaris which needs to disable the hardware RAID to do
> its error correction and compression.  It gets patches automatically with
> the OS (similar to yum/apt-get).

-- 
Warren Luebkeman
Founder, COO
Resara LLC
1.888.357.9195
www.resara.com