Three months past since time i have opened case in Symantec about a problem with slows speed backup. Case was in backup speed problem, i did not see any load on CPU, memory or storage subsystem, but speed was very slow. I was performing thousands of tests of my storage subsystem to verify that there was no problem. I have asked on this forum for people who faced with the same problem, i have received a lot of recommendation (thank you for that), but nothing help.
Today i have received last message that actually finish my searches:
Backup Exec works in a single stream and then divides that stream as the number of backup jobs are increased. Hence they will see slow performance when the number of jobs are more and again .. this is by design of the software.
So, when you calculate backup speed for Backup Exec, you should perform IOmetr tests on source and destination storages using 64KB block size, parameter Outstanding IO should be 1 and one Worker should be used (by default as much workers as you have CPU cores). You cannot perform backups on speed more than you get with IOmetr (exeption client side deduplication). If you use GRT, than backup speed may be much slower (up to 10 times).
Clarifications are welcome.
