Size limit of shadow copies

[Guest 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

[Guest Ryan Hanisco]

RE: Size limit of shadow copies

 

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

>

>

>

[Guest Jeremy]

Re: Size limit of shadow copies

 

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

>