Re: Oracle + LVM = Mirrored Backups?

Useful summary, but a couple of comments interleaved.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

GDN wrote in message <814cu4$dei$1_at_news0.skynet.be>...
>When you have HP-UX and Mirrordisk UX you can use the following procedure
to
>take a full off-line backup with a minimum downtime.
>
>1. Shutdown the db
>
>2. use "lvsplit" to "unmirror" the lv's. This will create several
>"backup-lv's"
>
>3. Startup the db. It's now running in a not-mirrored state. The db is
>available for the users or batch jobs.

I believe some sites run with a triple-mirror to avoid the risk. The side-effect of having only half the spindles for I/O is also a potential performance problem to consider.

>
>4. use fsck + mount to create usable file-systems from the
"backup-lv's".
>
>5. take a backup of the "backup-filesystems"
>
>6. dismount the "backup-filesystems"
>
>7. use lvmerge to synchronize the mirroring.
>
>8. Done, you have an offline backup. The db is running again on mirrored
>lv's.
>

There could be a significant time-lag before the mirrors are resilvered, and the I/O overhead of resilvering could have a hefty impact on performance.

>Be carefull with the lvmerge command. The order of the lv's you specify
>determine the lv's that will be syncronized.

Happy memories - was it only 10 years ago I saw an HP engineer put in a replacement disk are resilver the wrong way round. Received on Fri Nov 19 1999 - 16:10:29 CST