Chris Robertson wrote:
> John Goerzen wrote:
>> extract it without using specialized tools.  It also makes me nervous
>> because it isn't a completely off-the-shelf implementation, and
>> doesn't appear to store a CRC in the file; is there integrity checking
>> anywhere?
>>   
> 
> http://backuppc.sourceforge.net/faq/BackupPC.html#compressed_file_format
> 
> and
> 
> http://backuppc.sourceforge.net/faq/BackupPC.html#backuppc_operation

Hi Chris,

Thanks for the pointers.  I had actually already seen that, but still
concerned about the lack of a CRC.  gzip doesn't have the problem that
the document is referencing, but even if it did, there are Perl modules
that can put a nice gzip header on the file.

>> Third, I'm wondering how well BackupPC deals with sparse files.  I
>> notice that the examples for tar are not giving -S to detect sparse
>> files.  Does BackupPC store sparse files efficiently, even if not
>> using compression?  On restoration, what will it do with sparse files
>> -- will it re-create the holes?
>>   
> 
> See 
> http://backuppc.sourceforge.net/faq/BackupPC.html#how_to_backup_a_client.  
> Specifically "$Conf{TarClientCmd}" or "$Conf{RsyncClientCmd}".  Adjust 
> the tar (or rsync) command to your preference.

That doesn't seem to be a full answer.

tar with -S will detect sparse files and write them to the archive that
way.  So if I back up a client with tar, it will send a compact
representation over to the BackupPC disk.  BackupPC, though, extracts
the files out of tar, compresses them, and writes them to disk.  To my
line of thinking, that completely eliminates the data about where the
sparse holes were.

This isn't a show-stopper, but it *is* vital information to know.

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