adding external backup storage device

[drkbeatz]

Hi All,

I have 5 ESX 4.0 servers in a farm. I am using vranger to backup images to a SAN and this is configured on a virtual machine. I would like to configure an external tape drive in the virtual machine to start backing up to tape.

Can anyone point me in the right direction please and tell me how to do it in a few easy steps?

Have been looking for some decent documentation on it but can not find anyything up to date on it.

Thanks

[VMmatty · Accepted solution]

Are you looking to do SCSI pass-through of the tape device directly to a virtual machine? While this works great, it does have quite a few limitations that you should be aware of:

1) It is only supported if you use SCSI cards found on the VMware HCL, of which there is not a large list.

2) Using this setup prevents the use of VMotion or HA as that VM becomes tied to the physical device on the ESX host.

Another alternative you should look into is a SCSI -> iSCSI converter device for that tape drive. That will allow you to present the tape drive to a virtual machine via the Microsoft iSCSI Initiator inside the virtual machine, which frees you from tying the tape drive/SCSI card to an individual ESX host or VM. You'll be able to use VMotion, DRS, HA, etc, while still being able to perform your backups with your usual backup software (Backup Exec, etc).

I've had good success with products from the following company. I think it's worth investigating and potentially spending another $1,000 for the flexibility this provides. Hope this helps.

http://www.attotech.com/products/category.php?id=2&catid=5

[drkbeatz]

Thanks very much for that.

is there anything that has not been thought of!! so I take it you would just put an IP address on this IP bridge device and just connect to to it via iSCSI initiator? Would it support any backup drive? would the server need any drivers for the tape drive to work?

[VMmatty]

The setup of the tape drive/IP bridge is pretty straightforward. The IP bridge gets an IP address and then you connect the tape drive (or tape library) directly to that via a SCSI cable. Then inside the virtual machine you use the MS iSCSI Initiator to connect to the IP bridge. Once you do that, you'll see the tape drive (or library) as new hardware inside the virtual machine just as if you had used SCSI pass-through.

There are no special drivers unless your tape backup software provides them. I know that Backup Exec, for example, has their own drivers that they recommend using and so you would install them. Once the device is visible inside the virtual machine you'll manage it as if it was physically connected.

You should speak with the IP bridge vendor regarding tape drive support. Some new tape drives are SAS drives which may not work with the IP bridge, so make sure it is compatible before purchasing it. We ran into a problem recently with a tape drive being SAS and not working with either SCSI pass-through or the IP bridge. We ended up returning it and getting a SCSI tape drive.

Speak with the vendor (either Atto or the vendor of your choice) to make sure your drive is compatible and then I'd consider this solution. To me the extra cost of the IP bridge is worth the extra flexibility you get from connecting to the tape drive via iSCSI.

[drkbeatz]

Hi

If you are using a fiber switch for san storage connected to your Vmware infrastructure does this also mean potentially vm's are tied to physical hardware meaning vmotion will also not work?

thanks

[VMmatty]

No, the fiber switch won't tie your VMs to a specific ESX host. You aren't passing through fiber channel hardware to the VMs (since storage is handled at the ESX layer). If you're referring to using Raw Device Mappings then you might have an issue depending on what mode you are using (physical vs. virtual compatability mode) but otherwise you should have no issue.