Size limit of shadow copies

[Calvin C.]

If I allocate only 3GB free space of Shadow copy for a volume where has more
than 30GB data, will it be able to create a shadow copy for all the files
the very 1st time? or apply to the changed files only? or I have to allocate
as close as possible to the size of our current data?

Thanks
Calvin

 

[Ryan Hanisco]

Calvin,

This will maintain 3GB of changes... this means that you'll have backups
for whatever period of time that lasts.
--
Ryan Hanisco
MCSE, MCTS: SQL 2005, Project+
Chicago, IL

Remember: Marking helpful answers helps everyone find the info they need
quickly.


"Calvin C." wrote:

> If I allocate only 3GB free space of Shadow copy for a volume where has more
> than 30GB data, will it be able to create a shadow copy for all the files
> the very 1st time? or apply to the changed files only? or I have to allocate
> as close as possible to the size of our current data?
>
> Thanks
> Calvin
>
>
>

 

[Jeremy]

The first "Shadow copy" doesn't actually save any data, it merely
check-points the volume so that it can detect the changed blocks for the
next snapshot. Then on the next snapshot it save the blocks that have
changed since last time. When you do a shadow copy restore it either
replaces the changed blocks with the ones from the shadow copy you are
restoring or in the case of restore by copy, it uses the original file and
the changed blocks to rebuild the file you desire.

So a 10% VSC quota will store a number of snapshots depending on the delta
data change between snapshots. This is quite hard to estimate before you
suck it and see since even if you do a file-level compare the VSC delta will
be less since it only counts the changed blocks, not the whole file like a
differential or incremental backup would.

VSC will store up to 64 snapshots and will discard the oldest one when it
runs out of disk space. It should never be considered as a replacement of
good backups since (unless you change the defaults) the snapshots are stored
on the same volume as the actual data, so a HDD crash will still toast all
your data.

Cheers,
Jeremy.

"Calvin C." <CalvinC@inbox.com> wrote in message
news:%23tYI5AXxHHA.4264@TK2MSFTNGP05.phx.gbl...
> If I allocate only 3GB free space of Shadow copy for a volume where has
> more than 30GB data, will it be able to create a shadow copy for all the
> files the very 1st time? or apply to the changed files only? or I have to
> allocate as close as possible to the size of our current data?
>
> Thanks
> Calvin
>