Re: copy to 2 different tapes?

=> On Sun, 23 Jul 2000 17:11:23 -0400, John Snyder <Snyder.John AT 
LMS.CANADATRUST DOT COM> said:

> I have some Very Important Data that I must ensure always exists in at least
> two separate places so that a media failure will never cause a data loss.
> This data happens to be DB2 (udb) logs; when a db2 client fills up a log file
> it will call a script to initiate a backup of that logfile.

> Then the log is backed up to a TSM server (3.7.3 on AIX sp nodes).  It goes to
> a storage pool on a raid group; once the backup has completed, db2 will feel
> free to re-use the original logfile space on the client.   So now I need to 
> get
> this data on two different tapes...one will eventually move offsite using the
> DRM component.

[ ... ]

You've gotten one suggestion, dealing with archives instead of backups; as an
aside, you might want to consider wether this type of storage is not better
suited for archive anyway.  (i.e. store these logfiles for X time, as opposed
to N copies of a changing file for X time...) But that's a digression.


Strong reccomendation: Make sure you have a big enough disk-pool "landing pad"
that you can store at least one "processing period' (day? shift?) of data on
it.

Then, you can

BACK STG LANDINGPAD COPYONE
BACK STG LANDINGPAD COPYTWO
[ ... ]
as many sets of belt and suspenders as your managament wants to buy tapes for.

This has several advantages, cheifly that you can simultaneously run one
backup session _per serial device_, rather than just one, period.  (or more
precisely, 'N', where 'N' is the number of volumes that need backing up.  In
most cases, that's one)

You can make five simultaneous copies from disk, if you have five serial
devices to catch them.


If this particular database gets hammered 24/7, then I suggest that you keep 2
(or more?) disk pools: size them appropriately, and then:

Every midnight, start tossing your logs to PAD2.  Backup PAD1 the requisite
number of times, and migrate it off to tape.

Every noon, start tossing logs to PAD1, backup PAD2, migrate to tape..

etc. etc. etc.



Allen S. Rout