How to determine best Netbackup fragment size
hi every body,
i use NBU 6.5 whit in one hand direct write on tape (LTO3) and in other hand primary backup ondisk (staging) and then destaging : writing of data from disk to tape.
So in my bakup i have several storage unit, in this storage unit are define a field : "fragment size",
i don't know realy what it's mean but i think it's cut the Big backup (ex: database og 50G) in smaller block and that's determine the size of this smaller block.
in a case of a error occur during the backup only one block is wrong and the backup is replay on this only one.
so the smallerthe fragment size are, the better it is.
But in a other hand i have tapes, and tapes prefer writing big block (for backup speed it's beter) and finding on block is easier and faster in case when we restor (the automate cartridge tape don't have a lot of point to check).
But if u have only one file to restore in the end of the block it's pretty long.
So for this first part i don't know if i m right, partially right, wrong, or totally wrong ^^
i have many king of data (Oracle database, mssql, files, ged, ...
i'm not in charge of the backup, but i have to learn about it and analyse it.
our fragment size configuration is : 524 288 Megabytes for staging disks
and 2048 Megabytes for LTO.
so what are the right choise for these fragments size? what are they linking to? how to determine best practice?
what is your experience about it ?