[rescue] Re: Small RAID array setup

Sandwich Maker adh at an.bradford.ma.us
Thu Jun 26 19:42:56 CDT 2003

"From: "Sheldon T. Hall" <shel at cmhcsys.com>
"For the last few years, I've been using a SPARCstation Classic as a
"fileserver on our little network.  Its single disk drive was large enough to
"store our critical data, and an attached DDS tape drive served to back it
"up.  The Classic has been running Solaris 7.
"Due to a new business venture, both the amount of data and its importance is
"changing.  I'd like to set up a small RAID system so that I can save more
"data, and do it more securely.  Naturally, I don't want to spend any money,
"but I have some stuff on hand I can use.  I have another Classic, a Sun 911
"case, and the 5 drives required to fill them.  All 5 drives are the same
"size, 4.5 gigs.  I also have a set of Solaris 9 install CDs. I plan to use
"the existing 2-4 gig DDS drive as backup.
"I would prefer security, capacity, and speed, in that order, for the RAID
"What would you suggest as the configuration most likely to achieve that?

my plan would require some additional hardware to increase security.

i'd get a sbse card, a second 911 [or similar] case, and a sixth 4.5G

one drive goes internal, and two in the case on the internal bus.
the other three go in the other case on the sbse scsibus.
using disksuite [or whatever they call it now]:
mirror your os partitions using the first disk on each bus.
	i make only / and /var and swap.  i put all remaining space in
mirror the remaining space of the first disk pair, and the remaining
disks so that one side of each mirror is on each bus.  stripe them.

any part of any disk can fail, and the worst that can happen is that
it won't autoboot, since that requires a quorum [>50%] of mirrors.
likewise, either scsi controller can fail with little impact.

reads will be faster, distributed across two buses.  writes will not
be faster, but not slower either as duplicate writes are dispatched in
parallel, one on each bus.

you could make a major speed/capacity trade by raid5ing /export
instead of striping mirrors, but i'd still keep the os mirrored.
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh at an.bradford.ma.us                       and think what none thought

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