RH 7.1 installation on an IBM server with 3 scsi disks

[Rick Stevens]

Andrew Kelly wrote:
> On Fri, 2004-03-05 at 18:03, Rick Stevens wrote:
> 
> 
>>Again, you can't have RAID5 on a single disk.  As to whether you can
>>install Linux on a RAID5 system, sure.  It depends on if it's a hardware
>>or software RAID as to how to do the install.
> 
> 
> Are you certain about this? 
> Of course it's not possible to have a hardware RAID with a single disk,
> but a single disk software RAID is completely doable. You just assign 
> partitions as container members.

Forgive me, but what in the heck do you gain by having a RAID made up
of a bunch of partitions on the same disk?  Unless you were doing it as
an intellectual exercize or to familiarize yourself with the tools, you
gain nothing.  There's no data redundancy except on the same disk and
you sure-as-heck aren't going to get any performance enhancements (if
anything it'll be slower).

Having a RAID using partitions on one drive is about as useful as teats
on a bull.  It shouldn't even be called RAID, but (pardon me) "RAIP"
(redundant array of inane partitions).  The whole point of a RAID is
to survive the death of a DRIVE.  If you start losing parts of
partitions, you had better replace the drive PDQ (pretty damned quick).

> I piddled around with software RAID on RH 9 ages ago, just wanting 
> to see how silly I could get. I don't remember all the details, but 
> I remember it having suprised me a bit. I'd build a 3 "disk" RAID 5 with
> 1 failover "disk", and then used the native tools to break it. I was
> able to kill things off until only a single "disk" was left. 
> I wasn't able to add "disks" and re-build the container once the RAID
> had been crippled to a single "disk", but the data was all still accessible
> and I was able to sucessfully backup "off site" and recover to a rebuilt
> system.

I agree that is could be a learning experience on how to handle the
tools, but it sure isn't practical.

> The whole experience was quite positive and caused me to re-think some
> criticsms I was developing.

Such as?
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
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