Summary backing up high performance disk sub-systems

[Loucks Guy <Guy.Loucks@xxxxxxxxxxxxxx>]

My many thanks to all respondents.

We have gone with clonesets, this has proved quite viable. We require about
25% of the disk set free. A second suggestion was using a hardware level
plex, but this still had the problem of mounting the fileset, unless you
just wanted to do a dd of the entire device.

The disk I/O overhead of the cloneset is not bad, we also regularly
defragment. Taking this off to DLT7000 has also helped.

Regs,

Guy

The best two were from:

alan@xxxxxxxxxxxxxxxxxx: who wrote
<TBA>

	The clone gets a copy of the unmodified page.  Once the first
	modification of a page is made, there's no need to update the
	clone again because it already has the unmodified page.  If
	you're using AdvFS, a cloneset is probably the better way to
	go.  Since you'd have been willing to commit enough extra
	space for a 3rd plex, you can use the extra space to get a
	feel for how much the database changes during the course of
	a cloneset backup.



Guy R. Loucks
Senior Unix Systems Administrator
Networks Branch
NSW Department of Education & Training
Information Technology Bureau
Direct +61 2 9942 9887
Fax +61 2 9942 9600
Mobile +61 (0)18 041 186
Email guy.loucks@xxxxxxxxxxxxxx