On Tuesday 16 May 2006 15:43, Christoph Pilgram wrote:
> Hi all,
>
> Because we have problems to hold our service level agreements with the
> customers for restoring big file-servers (10 Mio files, 1TB disk-space
> in one filesystem), we are thinking about storing the backups not
> anymore on tape but on disk. Does anybody has experience with that kind
> of storage-pool for about 40 TB of backup data ? Does anybody use for
> example a "Data Domain DD460" or other systems using COS to reduce the
> amount of data.
We have lots of small customer with storage pools around 5TB.  A LTO library
with 2 tape drives can handle the backup, but the problem is restores.
Restoring a file or a oracle db is ok.
But for each restore, you have to check if a tape drive is free.  And
restoring multiple servers and/or file systems creates a mount point
bottleneck.

The solution is to migrate existing customers to a SATA based SAN disk pool
(DS4100, or similar) and doing disk-to-disk backup. The existing library can
be used as electronic vaulting (if you can put the disk SATA pool and the
library in a different building).
For new customers, we are suggesting a SATA base disk pool and the smallest
library (NOT tape loader) you can find with 1 tape drive for the offsite
backups.  (You only need 1 tape drive for the migration.)

Right now I have a customer with a random storage pool on a DS4100 with SATA
disks and it's running fine.  I'm implementing an other one, also random
storage pools on a DS4500 with also SATA disks.
I'm not going for sequential disk pools because I don't want the overhead of
reclamation.  The SATA disk pools are on a remote SAN and if I have  to do
reclamation on a remote storage pool, I have to copy data 3 times over the
SAN (1: backup, 2+3: relcamation).

Stef