Volume Shadow Looms Large
Gotchas from readers who've implemented Windows' Volume Shadow Copy Service.
- By Bill Boswell
, I discussed some gotchas to watch out for when
deploying the Shadow Copy for Shared Folders feature in Windows Server
2003. I invited readers to send me additional items and I got some great
Bob Wilson, who works for Computer Sciences Corporation, submitted a
heads-up on an issue that he discovered. In brief, he says that if you
right-click a Dfs folder in a Terminal Server session, you may not see
a Previous Versions tab even though the Previous Versions client has been
installed on the terminal server. This happens if the Dfs root is hosted
on a Windows 2000 Domain Controller or a Windows Server 2003 Domain Controller
that does not have the Shadow Copy for Shared Folders feature enabled.
A patch for this problem is available in a hotfix at KB article 887189:
"The Previous Versions tab for a file or for a folder in a DFS share
is not displayed in Windows Server 2003 and in Windows XP."
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Ron Rynbrandt, who works for the Dr Pepper 7UP Bottling Group, wrote:
We use VSS for shared folders, and we love it. I store all of my Citrix
user folders and profiles on a server where I use VSS as a restoration
tool. It replaces about 95 percent of all restores we perform, and reduces
restoration times from 2-3 hours (from tape) to about five minutes.
We do restrict usage of VSS restores to just IT people as part of our
change control process.
One small caveat: When I first set up VSS, I let it use unlimited
space on the drive. This worked okay for a while, until the drive got
close to full. Then, when the VSS service ran again, it ran out of disk
space and corrupted all VSS images on the drive. This happened a couple
times before I set a limit on VSS space to 5 MB less than the capacity
of the drive. Now, VSS images are handled in a FIFO order correctly.
Falco Dam, who works for IT-to-IT, a training and consultancy company
in The Netherlands, had several important items to watch out for when
I have worked with VSC in several environments and would like to point
out another few gotchas for those people considering to implement this
Volume shadow copies can only be enabled on an entire volume. If at
all possible, try to find out what data would need VSC and place that
on a separate volume. You do not want, e.g., roaming profiles hogging
up your precious VSC space.
You can only set the amount of space reserved for VSC, not the number
of shadow copies. How many shadow copies you can go back, therefore,
depends on the activity on the volume. I've found it quite difficult
to predict up front the number of saved shadow copies you will have
available at any one time; you only know when you've implemented it.
A tip would be to hold open the possibility to assign more disk space
to VSC if needed.
You always run the (albeit minimal) risk of overwhelming the Volume
Shadow Copy Service, which causes all of your shadow copies to be deleted.
This risk can be mitigated by placing the VSC data on a separate spindle
of disks, making sure you have enough resources, and installing SP1
which includes KB 833167
as you've pointed out. Still, you need to be aware of this risk.
Any backups you make (using NTBackup or any other tool) will only back
up the current data. There is no way that the shadow copies themselves
can be backed up (none that I know of, anyway). You may want to consider
redundancy in the spindle that you use to hold the VSC data.
As for the Previous Versions client, I am always wary to just install
it on any workstation. I'd hate to see some clueless user playing with
it and restoring a massive folder from a shadow copy with a single click.
There's just no way to undo this damage. My advice is to install the
Previous Versions client on administrators' computers only and perhaps
some power users.
Thanks to Ron, Bob, and Falco and to everyone who writes in with great
information to share with the readers of this column.
Contributing Editor Bill Boswell, MCSE, is the principal of Bill Boswell Consulting, Inc. He's the author of Inside Windows Server 2003 and Learning Exchange Server 2003 both from Addison Wesley. Bill is also Redmond magazine's "Windows Insider" columnist and a speaker at MCP Magazine's TechMentor Conferences.