Disk Recovery suggestions welcomed...

[Kent Borg]

On Thu, Dec 15, 2005 at 09:42:34PM -0500, Rich Braun wrote:
> Get two and mirror them using RAID1.

Let me second (third?) the suggestion to use software raid 1.  Great
stuff.  Use it.

Two cautions:

 1. Just because you are using raid 1 doesn't mean you don't have to
    worry about hardware problems.  An external nasty thing that
    happens to your machine (overheating?, power glitch?, flood?,
    knocked over really, really hard?) might take out both disks.
    Also, if one disk dies, you will keep running, but at that point
    you *have* to get a replacement quickly.  The next disk might
    shortly die of the same, say, overheating.  (Two disks where there
    were two create more heat.  You might want a case fan.)

 2. Just because you have a hardware mirror doesn't make it any easier
    to go back in time to recover from some operator error ("nohup rf
    -rf /").  Backups are the way to go back in time to get data from
    before the stupid mistake; even with raid 1 you need backups.
    (On-disk backups, on a different partition that isn't normally
    mounted, can work pretty well.  Not perfect, but better than
    nothing.)

And another plug for Linux software raid: it is well tested, works,
even improves performance.  Hardware raid, however, is more scary.
The hardware isn't as well tested, it might make mistakes with your
date (I have heard stories).  The special raid hardware itself might
fail leaving you looking for a specialized spare part that could be
both expensive and hard to find.  Finally, some "hardware" raid is
mostly just a dongle and requires special software to use it--software
which also isn't as well tested as the software raid in Linux.  

Linux software raid 1 rocks.  It is even bootable.  You should put
your swap on raid too.


-kb