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Re: snapshot able FS



On Fri, 21 Jul 2000, Alex Chudnovsky wrote:

> On Fri, 21 Jul 2000, Ben-Nes Michael wrote:
> > what is file snapshot ?
> 
> All your files as they are for some moment are copied aside and 
> frozen - automagically by the file server, and if I'm not mistaken, you 
> address them by the same names plus some addition. In case you need, you can 
> use the snapshot to restore lost/screwed/etc files.

the way it is done on Netapp is somehow by keeping just diffs. basicly
for every NFS export you define on it, it creates a .snapshot directory
or more, so you can always keep two snapshots of 1 and two hours ago,
another of the last midnight, etc, in essence:

if /var/spool is mounted from a netappliance, you will have
/var/spool/.snapshot/hourly.0, and hourly.1, daily.0 etc. the point is
that is /var/spool/mail/username was somehow killed, mangled, deleted,
or whatnot, /var/spool/.snapshot/hourly.0/mail/username is still there
from the last snapshot event (classicly from the last round hour) and
the same with /var/spool/.snapshot/daily.0/mail/username to get the file
excatly as it was at midnight.

-- 
Ira Abramov, GNU/Linux advocate.
(@-     
//\     "Akamai, Google, MicroSoft, Sun, Oracle, Intel, NASA, Sony, 
v_/_    Python, JPG, PNG - CS masturbation is changing the world."
                          -- C.S. answering to Linus, 3/7/2000



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