Edward Chow wrote:
> We setup the new e-smith 5.6 server
> and use the Hp surestore DAT40
> , DDS-4 20/40GB tape
> to backup the system.
>
> Server storage:
> ----------------------------------------------------------------------------------
> Filesystem Size Used Avail Use% Mounted on
> /dev/sda3 33G 25G 6.9G 78% /
[...]
> I check the backup log and see the message:
> buffer (writer): write of data failed: No space left on device
>
> What problem occur?
Been there, seen that...
As you guessed, the problem is that the tape is full.
Using backup devices one must keep in mind that their real available capacity is the first figure; the second one is an estimate of what can be stored if the data can be compressed with a 2:1 ratio.
So, you hav to think about your tape unit as a 20 GB one.
If a system contains many already compressed files - zipped or gzipped files, jpeg images i.e. the ones in the squid cache, it can happen that the mean compression ratio is way lower that the estimated 2:1, or worse, lower than 1:1 - the subsequent compression actually increas the size of the already compressed files.
Can your server fall in this cathegory?
By default flexbackup compresses data with gzip before saving them on tape, that in turn compresses the data stream again, so it can happen that the net result is a slightly expanded save set.
If you want an optimized backup operation, you should experiment with flexbackup parameters - block size (32 KB?), compression on/off, data backup utility (tar vs. dump), and maybe a different backup strategy, making more selective backups of different file system subtrees.
Or you can simply keep your disk lean - or buy a larger capacity backup unit
--
Pierluigi Miranda
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