Paul Blackburn <[EMAIL PROTECTED]> writes:
> How do you work out how much disk space to allow for Backup volumes?
You need to get a feel for how much data turnover you get on your RW
volumes. Note that this is a good reason to run frequent (i.e., daily)
backups.
> I understand that if the ReadWrite volume contents do not change between
> runs of "/usr/afs/bin/vos backupsys -prefix user -localauth" then the
> Backup volume requires little space in addition to the space used by the
> ReadWrite volume. If there is change then space is needed for new data.
>
> Have I got this right?
Essentially. There is a copy-on-write bit in the vnode - if the
fileserver writes to a vnode with the bit on it allocates a new vnode
for the data and turns off the COW bit. The BK volume hangs onto the
old data, and the RW volume slowly splits itself away over time.
dan
