general question regarding images on tapes

[oskhan]

hi all

I am new(freshman at college)(first time) to using veritas and tapes to take backups. I hope some one can put my mind at ease by confirming my assumptions

" say I was using only 1 tape(A) to take cumulative incremental backups(ret period 2 weeks) on Mon, Wed , Fri and full backups every Saturday(on a different tape).

so content of tape A druing 1st week, will be images - a,b,c
and during second week - a, b, c, d, e, f

By monday (third week) the image 'a' will have expired and say the backups was of a size larger than the image 'a'. I know that images are written sequentially on a tape, so the tape contains these images in the following order- b,c,d,e,f . Now when vnbkup is doing a backup, it will keep writing in front of image f till the tape finishes and then will rewind to fill in the space which image 'a' used to occupy. Right??

Also, if it requires more space, it is not going to overwrite the image b, rather it will use the tape in the scratch pool. Right?

forgive me if this is basic knowledge, however I wish to be assured rather than make any assumption and suffer in the process

thanks
os

 

[Stumpr]

> Now when vnbkup is doing a backup, it will keep writing in front of image f till the tape finishes and then will rewind to fill in the space which image 'a' used to occupy. Right??

NO...
The area on the tape will not become available until ALL images on the tape expire. Then the entire tape will become available.

Please read this post for more info

http://www.tek-tips.com/viewthread.cfm?qid=1062470&page=1

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