Very slow backup

[Kalle_Saarinen]

Hello,
I just installed BE 10d to a new Dell PE2950 server using Dell PoverVault 124T changer via SCSI. So the installation, server and storage are brand new.
I have done a few test backups (with and without HW compression) from the local BE media server and I getting very poor throughput rates. My test backup includes files from local servers C & D drives total of 650Mb. Throughput rates I get vary between 3-4Mb per minute. Tape drives native uncompressed speed is 245 GB/hr so I'm way below. Now backing up and verifying this 650Mb test set takes over 5 hours!

So far I have: read this forum, installed new drivers to the backup drive from Symantec, verified that I'm using latest firmware, installed BE 10d SP1 and avalable hotfixes, verified the SCSI connection for HW conflicts. This hasn't helped.

So what else there's to do?

[Kalle_Saarinen]

Few things I forgot to mention. The backup starts a bit faster and then slows down towards the end. Also this can't be a network issue cause I'm not backing up over network. There are also plenty on system resources on the host server. It's using under 2% of processor(s) capasity and under 10% of system memory. There's also lots of free space on the drives.

[Ken_Putnam]

From the devices tab, Right click the tape drive\Properties

What are the settings for Block Size,. Buffer Size and Number of Buffers, both Single Block settings and both Pass Through settings?


Are the Tape Drive and Library on their own SCSI controller?

[Kalle_Saarinen]

Thanks Ken.

They are the defaults.

Block size: 64k
Buffer size: 64k
Buffer Count: 10k
High Water Count: 0

Read single block mode: unchecked
Write single block mode: checked
Read SCSI pass-through mode: unchecked
Write SCSI pass-through mode: checked

Drive and the changer are on their own SCSI adapter (Adaptec 39320A Ultra 320).

I can't find any write errors or SCSI errors anywhere.

[Kalle_Saarinen]

OK. So I increased the buffer and block size and the number of buffers. Now when trying the same test set. The first 100Mb goes really fast.(to the buffer memory I assume) and then I significantly slows down. When the actual writing to tape takes place. So how to configure the drive to increase write performance?

Thanks.

[Kalle_Saarinen]

The problem was a wrong type of SCSI adapter. I had 320 should hava had 160. So this one is solved. Now I get an average over 800Mb/min throuhgput...

[David_Webb]

Kalle,


The 320 will work fine. You have to make sure that you are using the NON-RAID driver s from Adaptec and that the domain validation is disab;ed within the SCSI BIOS.

[Ken_Putnam]

For locally attached SCSI devices all of the single block and pass thru should NOT be checked

If the single block write box is checked, BackupExec will totally ignore any buffering you specify