On Thu, 18 Jan 2001, Joi Ellis wrote:
> On Thu, 18 Jan 2001, Martin Apel wrote:
>
> >On Wed, 17 Jan 2001, Joi Ellis wrote:
> >
> >>
> >> I amflush these to tapes to send to offsite storage.
> >> I've already done two tapes from this batch, I have four
> >> left to do.
> >
> >That's a nice idea, but I have more data to back up than fits on the
> >holding disk, so I have to flush some dumps to tape in order to dump
> >all filesystems completely.
> >
> >Martin
>
> So? I was trying to point out that simply selecting the biggest
> dump may not give you the best packing. Often, the few tapes contain
> four or five smaller dumps and can obtain a 99.8% usage rate.
>
> The total amount of data to be backed up has no effect, since you can
> only flush what's on the holding disk.
Yes, you are right. You might achieve a better packing by a more intelligent
algorithm. But after you wrote out the first dump, things might have changed already
because another dump has been finished in the meantime. I used this scheme for a few
months now and it gives me usage ratios close to 100 % for all but the last tape.
But this only works if you have a good mix of file system sizes.
Greetings,
Martin
