[Info-vax] NetBackup Performance Woes

[Stephen Hoffman]

On 2015-05-20 21:15:40 +0000, Geek Nerdly said:

> It's very consistent:
> 
> Queue Length spikes to as high as 50 and does not dip below 3 on node B 
> (where backup runs) while backup is running, where at the same time on 
> node A Queue Length hovers between 0 & 1.

That's a disk volume that's saturated, or potentially an HBA or storage 
controller that's saturated.

Any disk I/O queue length past 0.5 means that half of all I/O requests 
are waiting.

Your backup tool has sufficient quotas and an I/O design that allows 
this load to be generated, unfortunately.

For an example of a throttling mechanism within the OpenVMS BACKUP 
tool, see HELP BACKUP /IO_LOAD on OpenVMS V8.3 and later.

Given the disk is apparently active at the time of the backup, the 
resulting archived may not be entirely consistent nor entirely 
reliable, either.


-- 
Pure Personal Opinion | HoffmanLabs LLC