Leigh,
I'm not sure if the documentation is out of date,
but it is still a valid recommendation. When you consider the time
it takes to back up and restore a 250 GB volume, this recommendation makes
sense. Our volumes average around 330 GB, and we see typical back
up times (on a level 0) of about 15 hours (to direct attached tape drives).
We have each volume split up into at least 3 qtrees (we try for four
if possible in order to dump one qtree to each tape drive attached to a
filer). Restore times are roughly the same as our backup times although
we haven't had too many requests to restore an entire volume, yet.
Of course, your milage will vary depending on tape devices, size of the
qtrees, whether it's a direct attached tape drive or 3-way NDMP, etc.
And with the filesystem overhead, snap reserve (set
to a high 20%), hot spares, etc., we have found that it's about 2 shelves
(14 disks) to a volume of 330 MB.
Leigh David Heyman wrote:
So, I've been through some docs, and they seem to
say that the maximum
"recommended" size of a single volume is 250G. With 36G drives
this equates
to basically 1 volume per shelf???!?!
Is this correct, or has the documentation in this regard not been updated?
Does anyon know what this "recommendation" is based on? It doesn't
seem very
efficient.
-Leigh
-----------------------------
A nasty looking dwarf throws a knife at you.
Geoff Hardin
Dallas Semiconductor MIS UNIX
geoff.hardin@dalsemi.com