Evren Yurtesen wrote:
>
> Also I see the --ignore-times option in rsync args for full backups. Why
> is this necessary exactly?
If you don't, you are trusting that every file that has the same name,
timestamp and length on the previous backup still matches the contents
on the target. It probably, mostly, usually, does... If you posted a
listing that showed the duration of fulls vs. incrementals, I think I
missed it, but it would show the difference in the extra
reading/comparison work on the server side. Even for incrementals you
still have to wade through the metadata for each file to find the
original length/timestamp/owner etc. which won't be the same as the
compressed/pooled file itself because those may be different for
different instances of the pooled contents.
The other side effect of doing a full - and the one you really need - is
that the complete directory structure is rebuilt as the base for
subsequent incrementals.
>> With tar, you never need to read the existing files so you are doing
>> much less work and you don't hold the remote directory in memory at all.
>> But if tar works better on your system, why not use it? The only real
>> drawback is that incremental runs won't catch old files in their new
>> positions under renamed directories. The full runs will straighten
>> this out.
>>
>
> Is it still possible to pool the files for saving disk space when using
> tar?
Yes, there is no difference in the pool handling with any of the
transfer methods. Tar and smb just have to transfer the file contents
before it can be matched against the pool. If you have plenty of
bandwidth this will happen faster than the rsync comparison. Also, tar
and smb incrementals use only the timestamp on the target to determine
what to back up so the server doesn't have to do extra work to compare.
> I wonder something, why cant backuppc set the backed up file
> modification times to
> match the client when backing up the files so it can compare the file
> modification
> time only at incrementals (and perhaps at full backups) like tar? In
> either case
> backuppc can do file by file checks when using rsync anyhow, but the
> limitations tar
> imposes would be removed, wouldnt it?
Tar doesn't have a way to do live comparisons. GNUtar does have a way
to detect renamed directories, but it requires saving a file on the
target machine.
--
Les Mikesell
[EMAIL PROTECTED]
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