Software RAID issues (was Re: Suggestions solicited, server bring up)

[Ben Scott]

On Wed, Nov 18, 2009 at 3:08 PM, Bill McGonigle <bill at bfccomputing.com> wrote:
> Yeah, if you've got local disk connectivity, software RAID is usually
> faster and more stable than hardware RAID, and is certainly more portable.

  Software RAID is portable across hardware, but not operating systems.

  Hardware RAID is portable across operating systems, but not hardware.

  In other words: I can't share a software RAID disk set between Linux
and Windows.  I can't share a hardware RAID disk set between Compaq
and Dell.  Which scenario is more likely to trouble any given person
will vary.  :)

  I've found hardware RAID to be more reliable when booting with a
degraded disk set.  A smart controller will just fail the bad member
disk and ignore it.  Software-based solutions -- which don't kick in
until the OS is running -- sometimes get caught up trying to boot from
a failed disk.

  If you've got CPU power to spare -- and these days, almost every
server does -- software RAID will generally be a lot faster than a
dedicated ASIC.  Cheap RAID controllers, especially, tend to be really
slow.

-- Ben