Woodsta,

Thanks, actually I put the SAN into production today and it did let me create a Snapshot with 250GB. We normally get about 20-40GB of changed data per day so I think that this Snapshot should be OK.

When you mean that "it will kill all the data snapped associated with it", that does mean that it will delete the original data too? I'm assuming no but just double-checking (first time using snapshots).

Thanks,
Mac

Hi There!

The general rule is 10% to 20% size of the actual virutal should be the free space reserved for snapshots with that the following rule used:

10% - Being pretty conservative for free space for the snapshot
20% - Being pretty liberal for free space for the snapshot

So, if we take your 6500G virtual disk for example, the free space on the AX150 to use for snapshots should work along the following lines:

10% = 650G
20% = 1300G <<<

The reason I recommend the 20% is because if the running snapshot runs out of free space it will kill the job and all data snapped associated with it, so you really always want to have the liberal amount of 20% setup.

Nothing say's you can't use the 250G though, and actually that may work. Kind of looks at the virtual disk and think about how often this virtual disk will receive writes. Does the data change often??? If the data does not change often or pretty infrequent you may be able to get by with just the 250G.

Hope that helps!

Tootles,
Woodsta

Hiya!

Oh no... your data on the virtual disk will still be there (does not effect your production virtual disk at all). I was referencing the "snap session" only. Meaning, if the snap cache runs out, the session stops and releases the reserved space (in this case the 250G) back to usage for any other snap sessions.

Yea, not to many write changes there on your server, you should be in good shape, just monitor the jobs (if you have notificaton setup, it will email you if a job fails which is really cool). If you want to get really fancy with it you can script out your snap sessions. Meaning, you can stop and expire and snap session and then start another.

http://www.emc.com/products/systems/clariion/ax150/support/faqs/How_do_I_script_snapshots.htm

The benefit of this gets a little indepth, but one step at a time young Jedi.


woodsta

I think I just found the answer to my own question.

It seems that I can only have one snapshot per virtual disk so if I want to have a snapshot at 12noon:

On the backup server at 11:55am:
admsnap_win2k3 deactivate -s snapsession

On the live server at 12:00pm:
admsnap_win2k3 stop -s snapsession -o ]my drive letter]:
admsnap_win2k3 start -s snapsession -o [my drive letter]:

On the backup server at 12:05pm:
admsnap_win2k3 activate -s snapsession -d [my drive letter]:

With this, I will the a point in time copy of the live server as it was at 12:00pm and it will remain for 23 hours and 50 minutes in the backup server. Am I correct?

MacAddict

Woodsta,

One more quick question.

If I want to have 3 snapshots of the live server: One at 9AM, one at 12noon and one at 5PM, would I schedule the following batch file at the following times?
8:55am, 11:55am, 4:55pm:
admsnap_win2k3 stop -s snapsession -o s:
admsnap_win2k3 start -s snapsession -o s:

And then in the backup server at:
9:00am, 12:00pm, 5:00pm
admsnap_win2k3 activate -s snapsession -d t:

If so, how do I remove them? My plan is to always have the 3 snpashots in total at all times (depending on how much space they take, might have to bring it down to 2...)

Thanks again!
MacAddcit

Sorry man, just got back to the forums. Here is a little tutorial which is helpful.

http://www.emc.com/products/systems/clariion/ax150/support/faqs/How_do_I_script_snapshots.htm


Your right, one snapshot per virutal disk, you probably figured this out already though.

(:

Woodsta