Calculating how long a restore will take. 1

[kuedm]

Does anyone have a current methodology to figure out how long a restore is likely to take?

Right down to factoring speed of NIC's, restoring to local versus SAN disk, number of tapes involved etc. etc.

My goal is to have a list of questions, in a spreadsheet, to ask a Storage Administrator which will then give a "best guess" at how long a restore will take.

Ideas? Links to references?

 

[Stumpr]

you will find exactly what you are looking for in this reference

VERITAS NetBackup (tm) Enterprise Server / Server 6.0 Backup Planning and Performance Tuning Guide for UNIX, Windows, and Linux

http://seer.support.veritas.com/docs/281842.htm

Bob Stump
Just because the VERITAS documentation states a certain thing does not make it a fact and that is truth.

 

[comtec17]

This is a very difficult question to answer as it will differ from host to host.

This is what I call the "It Depends" factors.

How many files are to be restored?
Was the backup multi-plexed?
How large is the restore?
What is the average size of the file? Are there many small files? >32k
Where are you restoring to? Internal disk (What is the rated throughput of the spindle and adapter) SAN Disk? How many I/O's will the LUN sustain?
What was the medium that the backup was written to and what is its read/write speed?

All these become factor and must be asked. My rule of thumb for backups with many small files, going to local disk is 2x-4x the time to backup. So if it took 3 hours to backup, I look at 6+ hours of restore time.

 

[Stumpr]

comtec is right.
There are so many variables. Another dependency is the setting of "max frament size" on the storage unit.

DOCUMENTATION: Why are file system restores are running very slow with large number of small files?

http://support.veritas.com/docs/279061

here is some more good reading
Slow restore performance

http://support.veritas.com/docs/230823

Methods to improve backup performance without adjusting VERITAS NetBackup (tm) buffer files

http://support.veritas.com/docs/260719

How NetBackup Full Restore works

http://support.veritas.com/docs/272323

I have seen restores take less time than the backups. I have seen restores take 6 times as longer than the backup.

Bob Stump
Just because the VERITAS documentation states a certain thing does not make it a fact and that is truth.

 

[mrn]

A rule of thumb is

"Twice as long as you expect and three times longer if it's really urgent"

Mike

"Whenever I dwell for any length of time on my own shortcomings, they gradually begin to seem mild, harmless, rather engaging little things, not at all like the staring defects in other people's characters."