Re: [cobalt-users] Re: Need to buy a new Raq

[Will DeHaan <will@xxxxxxxxxx>]

Kris Dahl wrote:

> This is very true.  RAID is designed to save you in the case of a single
> disk failure.  However, I am not sure if the software RAID employed on the
> Raq4 will accomplish this or not.  Sure your *data* will still be there but
> the box will be down, right?

Maybe on RedHat, but not on Cobalt Linux.

We've worked on the Linux IDE drivers to better tolerate drive
failures.  If a drive fails, the server will continue to operate so long
as the drive failure doesn't also break another component such as the
power supply.  I've never heard of the latter case happening so I think
that would be rather unlikely.  

> > As a side note, since Cobalt uses standard IDE drives, the
> > reliability on these drives is not too good - Mirroring the drives in
> > them is a good idea...

The hardware for "server" SCSI and "workstation" IDE drives of the same
spindle speeds, capacities and manufacturer are identical besides the
circuit board controllers which rarely fail.  This is a common
reliability misconception of IDE vs. SCSI.  I sure appreciate replacing
$140 ATA drives over $500 SCSI's.

> And this is not hardware RAID, nor is it hot-swappable.  I am firmly of the
> opinion that if you have a single production server (that is not a load
> balanced cluster) you need to have hot swap hardware RAID on the server.
> 
> -k

Hot swap is nice, and Cobalt understands the value of that feature even
though it's not present on the RaQ 4.  The RaQ 4r will allow operation
_with_ a failed drive allowing you to replace a disk during off-hours,
at your leisure, off-line.  You'll get email notification of a drive
failure and detailed RAID web status reporting. 

While the RAID 1 configuration is not done in hardware, it is optimized
and poses very, very little performance impact and in some cases a
performance increase.


	-- Will