Low performance with Networker and LTO Ultrium Tapes

[ejgarcia]

Hi all,

I have an environment with WIndows 2000, Networker 6.2, L20 StorageTek jukebox, scsi connection (adaptec 29160) and 1 Tape LTO Ultrium drive. The rate or speed of the tape, in theory, is 15MB/Sg. When I perform a backup the speed of the write doesn't increase more than 1.5MB/Sg

I've tried all of Networker environment variables, All registry keys for scsi cards, and don't know what's going on.. The block size on Legato are set up to 256K. The mt command shows me that the OS has 256k too.

Thanks

 

[ulsj]

Hi!

I have hade this exact problem on a SDLT drive.
I saw preformans at 1,5 mb/s on one drive and if I split the backups on two drives then the sum of both drives whas 1,5 mb/s. This was resolved after i changed the IRQ on the scsi card.

/Ulf

 

[TDun]

As ulsj said, check the IRQ for the scsi card and see if yout can change it to a unique one (not shared with other controllers).
Also, are you multi-plexing your data (if there more than one savestream writing at once)? If not, then you will get degraded performance as there is not enough data getting to the drive to keep it busy, so it is working in stops and starts, giving a low speed.
Have you tried any other utility (including NTBackup) to write to the tapes? What performance do you get with that?

 

[rgzimmer]

Maybe the client you're backing up can only send data at that rate. There are a large number of things to look at. I have some servers that avg. 12MB/min on my LTO's while others are lucky it hit 1MB.

What kind of performance do you get when the backup server backs itself up?

 

[TBornemann]

Hi,

that's a problem between the IBM-Drive and the Adaptec driver.
We had the same problem here. With the IBM Neptune drivers it works.
Call IBM for this drivers.

\bye
thomas