gimili wrote:
> On 7/12/11 2:31 AM, Andrew Ford wrote:
>> My setup is somewhat simpler.  My BackupPC datastore is stored on a
>> 700GB LVM logical volume on a 1TB disk, and I have 3 external 1TB eSATA
>> disks.  Each week I make a snapshot of the BackupPC logical volume and
>> "dd" the snapshot volume to one of the external disks (takes about 2
>> hours) and then "cmp" the snapshot volume and the raw partition on the
>> external disk.  The newest backup disk lives at home, I take the next
>> oldest in to work and keep it in my desk, and bring the oldest disk 
>> home.
>>
>> Andrew
>>
>
> Simple is good.  I also use 3 external eSATA drives.  I haven't tried 
> this yet but I was considering using a cron job to run the command 
> line command that generates a large tar file of the backup.  I had a 
> complete hard disk failure 7 months ago and this was how I moved the 
> data from the backuppc machine to the new replacement drive on my 
> server.  The only thing I would have to do is remember to cycle the 
> disks.
>
> Any comments on pros/cons to this method?
>
> Thank you,
>
Generating a tar file of the backup directory is going to walk the 
directory tree and read each of the files separately.  Doing a "dd" of 
the snapshot volume is reading the disk sequentially (although there may 
be a certain amount of out-of-order data if there has been any activity 
on the underlying volume).  Originally I was doing a recursive copy of 
the filesystem of the snapshot volume to the external disk, but that 
took much much longer than the block copy (I think it took something 
like 30 hours compared to 2).  I suspect that making a tar file is going 
to take something in between the two extremes.

Andrew

-- 
Andrew Ford
South Wing Compton House
Compton Green, Redmarley
Gloucester, GL19 3JB, UK
Telephone: +44 1531 829900
Mobile:    +44 7785 258278


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