On 7/1/06, Giblin Dean L. <DLGiblin at vasc.com> wrote:
> Backup Performance ? The 8GB/Min Goal
      < roughly 140MB/sec, continuous for 8 hrs >

> Our future storage space requirements were estimated to be 4 TB. Our
> requirement is to complete the backups within an 8 hour window.  To meet
> this objective required a backup solution that could provide an 8 GB/Min
> solution.

> Hardware:    <summarized>
> DL580 G3 ,  Dual Processor, 4GB, LSI 320 to tape, HP RAID controller
> MSA30 DB ,      14x  15K, 146 GB
> MSL6030,         Dual LTO 3

> ·        HP SCSI drivers for Microsoft Windows have a 64K block size
> limitation. All the test tools which could bypass this driver and set
> communication parameters on the SCSI bus obtained increased performance. All 
> of the applications which utilized the system driver suffered.

Supposedly there are Veritas drivers for windows that are faster.  See
previous discussions.

> Our original design was to implement a RAID 10 solution using two 7 disk
> RAID 0 arrays. This results in 490 GB of storage and approximately 1.8
> GB/min data rate.

A 7x 146 GB RAID 5 array should EASILY give you 100MB/sec read
performance.  Probably much better.

The key to speed in NetBackup is SEPARATE I/O CHANNELS!  There is a
great performance document (which I can't find right now) that shows
how Oracle, Sun and Veritas demonstrated a 1TB/hr setup several years
ago.

Using 2 separate U320 SCSI channels you should be able to have both
halves of the MSA30-DB spitting out 100MB/sec or more.

Each LTO-3 tape drive needs its own U320 SCSI channel.  (The robotics
can piggyback on one of those channels.)

The system disks in the server itself need a separate SCSI channel as
well.  That brings us to a total of 5 separate high-speed SCSI
channels.  If you don't currently have 5 separate channels, you need
to add some of these: http://lsi.com/products/scsi_hbas/lsiu320.html

The other side of the equation is the network performance.  To backup
a NAS box over the network you need to optimize the network path.
Jumbo frames will probably help.  Aggregating 2 gigabit ports might
help too.   You didn't say how many other clients will be backing up
over the network.  If there are many clients, spread them across
multiple gigabit interfaces on the server.

To keep the LTO-3 drives happy, you need to feed them at least 40
MB/sec.  To meet your design goal of 8 GB/min you need to continuously
feed 2 drives @ 70 MB/sec each.  That will be fairly difficult and
will probably require 4 separate gigabit interfaces.  I suggest adding
one of these to the two built-in NICs:
http://intel.com/network/connectivity/products/pro1000mt_dual_server_adapter.htm

The difficulty lies in having the clients produce data that fast.  You
will most likely need to have the client data streams multiplexed @ 4
or 8 streams per tape drive.
Disk staging is useful for slow clients, but is probably a negative
factor for the NAS box.

Here's my summary:
- Add I/O channels for a total of 4 gigabit Ethernet and 5 U320 SCSI channels.
- Optimize the network between the NAS box and the backup server.
- Send the NAS data directly to a single tape drive.
- Configure 1 LTO-3 tape drive per SCSI channel
- Configure 1 RAID5 array per SCSI channel
- Separate the system disks from the backup SCSI channels
- Use a High MPX on client backups to tape.
- Use disk staging only for VERY slow clients.
- Use the Vertias drivers where available, not Microsoft or HP.

You need to be able to read or write at over 100 MB/sec on each SCSI
channel and you will need to read from the network at over 50MB/sec on
each Gigabit interface ALL AT THE SAME TIME.  With a Solid PCI-X
backplane (like the DL 580G3 has) this is entirely reasonable.

Austin Murphy