SnapShot VS SnapClone for Boot san

[CA1239446]

Hello,

I've got one W2K3 server which use boot san. The LUN is stored on full disk group. I'd like to use snapclone for bootsan and represent this new volume to my W2K3 node.

What are the best practices for cloning data like OS ?
Can you say me, what are differences between snapshot and snapclone ? I know that the snapclone is not available until the snap is finished...

I use EVA 5000 storageWorks with RSM for my tests.

Thank you

[Chris Rosan]

I would not recommend using snap clone for O/S installation on windows. You'll find that you'll have problems with SID's especially if you're using active directory.

I recommend you use HP RDP to deploy the servers. It's easy to setup and will quickly setup your entire server.

[Geoff Orwiler]

Anthony,

The difference between snapclone and snapshot on the EVA is that the snapclone is a full copy of the vdisk. A snapshot is only the data that has been changed with pointers back to the unchanged data.

To do the data migration as you are suggesting will work very well with snapclone. Also, snapclones are immediately available to the host. The EVA will do the rest of the copy operation in the background. I have done this many times and it works well every time.

Make a snapclone of the system drive, shutdown the host. Unpresent the original vdisk from the host, present the new one. Power server back on and go into BIOS settings for the HBA. Ensure the correct boot lun appears and then reboot the host. Your done!

[CA1239446]

I understand the snapclone mecanism. You says for snapshot, that only the data modified are snap. The snapshot is like that "differential backup" ?

i've realized the same test of yours. But, I would like to know if the snapclone can be make with the OS booted ? there is a risk with this os cloned ?

[Chris Rosan]

A snapshot can't be presented to another server, only a snap clone can. Snapshot is good for situations such as if you're doing an upgrade and want to easily roll back.

A snapclone creates a totally independant backup of the data.

As i said before, if you do this, then the SID's that are generated on installation will also be duplicated. I tried doing this last year and had different sorts of problems left and right. I've also made "copies" of virtual machine disk files to make another copy of a virtual machine and we've had problems with this (it's basically exactly the same thing).

If it's a production environment i STRONGLY recommend that you DON'T do it. As previously mentioned, use HP's RDP product. It's quite good and HP have developed all the scripts for you to setup bios & Array cards, & installing O/S.

If you want to clone other data then that's fine. I use snapclone every night to perform a system backup of 35G of data in about 30 seconds.

Also, if a snapshot of a LUN exists, you can't snapclone it until you remove the snap shot.

I'm sure that there is a good use for snapshot but i've never found a useful one. I always use snapclone for making copies of data.

It will be particulary handy in cases such as making a copy of "production" data to present to a "development" environment.

I did recently try and use snapclone for backing up windows servers by cloning the data and presenting to another host to be backed up, but i wasn't successful (without a lot of effort) in automating it as windows didn't seem to like it. I believe it can be done, but backup over network or direct to the SAN with a tape library is probably a MUCH easier option, especially with the price of this hardware dropping.

[Uwe Zessin]

> A snapshot can't be presented to another server,

Ahem, that feature has been in the EVA since version 1. The ability to do a snapshot rollback is rather new.

[CA1239446]

In fact my operation will be to move the OS to another Disk group.

The server will be identical.

I''ve no choice, I must do a snapclone for this operation. If I can do without shutdown the server, i'll do. But, which state the os after this changes...