DLT7000 and Network Backup Speed

[Shaliko]

I have a DLT7000 with 7 tape autoloader. Operation works reasonably well except for speed. ANY network resource that gets backed up is only operating at around 20mb per min. THis is just too slow for the amount of data I have to deal with (> 100gb). I have implemented the Veritas recommendation of reducing the scsi bus speed down to 20mb/s (from 40 default) with no change.
Obvious things like network traffic etc have already been evaluated. Speed is constant at around 20mb/s regardless of network activity.
Any ideas on how to increase the speed? We are using the hardware compression option. NT4 Server is well spec'd and up to the task.
Any input appreciated.
Tks
Rgds Neil

 

[mikey1074]

Neil,
I have the same problem, but unfortunately I haven't found a solution yet. I'm running NT 4.0/SP 5, Dell Poweredge w/ 800 mhz Pentium III, 128 MB RAM Intel 100bT Dual Port server nics running IP/IPX (backing up Netware servers as well) Running Backup Exec 8.0, build 3315. This is the ONLY function of this server. Connected to a 7 magazine auto-loader w/ dual DLT 7000 drives.
I'm getting a max close to 20 MB/minute also. I haven't found a solution yet, but if I run across something, I'll try and post my findings here.

Mike

 

[Zelandakh]

Try sticking some data on the local machine and backing that up. If that runs faster then it is a network issue, if it is the same speed then your problem is BE.

 

[Tilo]

Shaliko

Have a look at these:

http://seer.support.veritas.com/docs/191807.htm

http://seer.support.veritas.com/docs/191793.htm

Also try this:

Try to perform the tests described below using a meaningful amount of data (at least over 100MB):

1. File copy:
Do a file copy of the amount of data chosen, from the target to the backup device. Time this file copy.

2. Backup:
Backup the same data as in point 1, and time the backup operation.

If the backup operation took a roughly similar amount of time to the file copy operation, then poor backup performance may not be a Backup Exec issue.

A backup operation will always be slower than copying data to a hard disk. Also each test below will give different results depending on the overall load on the network at a given time. However, this will serve as a benchmark.



Half duplex Full-duplex auto negotiation:
The auto negotiation feature may sometimes result in a slower packet exchange between computers, than if forcing all networking equipment to either half or full duplex. Try to change ALL hubs/switches and NICs to FORCED Full or half duplex. It is important to note that to be effective this change has to be implemented on all the connectivity equipment between the 2 devices to include the NICs as well as the hubs and switches.

Compare the performances between half and full duplex:
If the network is running on full duplex change to half duplex, or vice versa. Note any differences in performance using the same amount of data as described in point 1.

Switch/hub statistics:
Some hubs and switches keep statistics, which you may consult either via a terminal typically plugged into a serial connection directly to the device or by using a management console. The statistics available will vary depending on the device, but you may typically look out for statistics on dropped packets, undersized or oversized packets, errors, etc...

Switch/hub issues:
Eliminate possible connectivity issues by using a cross-over cable between the 2 devices.

Bandwidth:
Monitor network bandwidth utilization during backups. You may use tools such as Network Monitor in NT or LANalyzer.

NIC drivers:
Ensure NIC drivers on both devices are up to date.

TILO