[Veritas-bu] Fragment Sizes...
dave-bu at graniteweb.com
Mon Mar 7 12:52:56 CST 2005
* william.d.brown at gsk.com <william.d.brown at gsk.com> [2005-03-07 16:27]:
> However a significant counter-argument, which many sites will find
> persuasive, is that the restore speed is also affected by the fragment
> size. In the extreme case, that you don't have a fragment size set at
> all, there is just one fragment on a tape. Any restore has to scan (at
> slow speed) the whole tape, reading it until the files required for
> restore are found. With fragments, the tape can skip forward at high
> speed to the required fragment (it is just a record to the tape); it then
> has to read just that fragment at slow speed to get the files. So unless
> you files are themselves >2GB, you would likely be happy with the 2GB
> fragment size. It really depends on your data, and how often you do
> restores, how quick they have to be...vs some improved write speed.
We have ours set to 2G for exactly this reason. we often have very large
backups >500G with restore requests that would take forever without
giving NBU a hint where to look for it.
david at graniteweb.com
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