Yes it is possible but you need to understand what is happening
to be able to set it up right. In order to do consolidate backups you
will need two read devices and a write device.
From my observations of consolidated backups over the last few
years, here's what is happening. Everything starts with a full (even if
that full was the last consolidated backup). For the consolidated backup
first thing that happens is Networker takes a level 1 backup. Networker
now has sufficient information to complete the consolidation. Having
finished that backup it then proceeds to do the consolidation. It does
this by reading both the full and the level 1 and comparing content
writing the result to the new, consolidated, full backup.
You can see from this that you require, at one stage, two
concurrent reads and a write. Now, pre 7.3.x it was only possible to
have a single read from a disk device. So, assuming pre 7.3.x, we will
need three devices (or at least two as we can read and write the same
disk device but performance suffers). So you can see, from above, that
the answer to your second question is yes, doing it with tape you will
need three tape drives to perform consolidated backups.
Be aware that the consolidation process can take quite a while,
sometimes giving the indication that nothing is happening as there is a
lot of 'under the covers' work going on and the write speed on the
consolidated full can appear disappointingly slow. But, it does do what
you want from a consolidated backup, cuts down the amount of traffic
that has to cross the network (even if it is at the expense of resources
at the Networker end).
>From: EMC NetWorker discussion
>[mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On Behalf Of mark wragge
>Sent: 18 May 2007 01:47
>To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
>Subject: [Networker] consolidated backups to disk?
>Is it possible to use disk devices for consolidated backups?
> Is it 100% necessary to have three tape devices as the
>networker admin guide states?
> Thank you!
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