Alan-
I've actually not used encryption, but certainly encryption will mean
that you will get no benefit from whatever compression your tape
hardware may be capable of--possibly doubling backup time right there,
if you were able to keep your tape drive writing at full speed. I do
know that encryption runs on the client and, I believe, is
single-threaded--I would expect that would at least account for a
doubling of the spooling time, since the SW encryption will dramatically
slow down the client. If you are not using spooling, then it is likely
that your tape drive is shoeshining now--which can dramatically increase
backup time and reduce tape & drive lifetime. Enabling spooling, if
you are not currently doing it, may help, if the tape drive is
shoeshining a lot.
If your tape library is capable (LTO4 or better, for example), you may
want to enable encryption in the drive, instead of in SW. If you can't
use encryption from the tape drive, then you may even consider doing
compression in SW as well--depending on your data this may
(surprisingly) help--less data to encrypt, and less data to write to
tape--but compression is also single threaded, IIRC, so that can easily
also make things even worse.
Sorry I can't be more help,
-se
On 6/8/2011 10:40 PM, Alan Langley wrote:
UNCLASSIFIED
Hi Everybody,
I've just setup encryption on our bacula backup using the explaination
in chapter 39 of the Bacula manual -- it has blown out our backup time
from overnight to 3 days ? Is this normal ? Is there any way to get
the time down? It is only backing up 1.5Tb onto a tape library
Alan Langley
Digital Preservation
Systems Manager
The National Archives of Australia
http://www.naa/gov/au
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