zoning tape drives between different SANS

[anton.mssm]

Hi, I have the following scenario.

I have a neo oveland 8000 with 12 drives. The first drive acts as a library controller. We just got 2 new 9506 switches and I am wondering can I split the library between the two sans. Now the two SANS we would like to have them not connected, not ISL to each other.

Will there be an issue with this setup because all the drives need to be together to talk to the library controller ?  thanks

[dynamoxxx]

correct, you want to keep both 9506 separate: Fabric A and Fabric B. As far as tape drives are concerned, are you going to use "shared" library mode where multiple backup applications will try to controller the picker ? If yes, then you need to make sure you connect those applications/HBAs to the same physical switch but if you just want to present some tape drives on fabric A and some drive on fabric B to the same backup application ..no issues there.

@dynamoxxx

[anton.mssm]

we have commvault and that is the only application that will control the robot/tapes. So I don thave to worry that if I put drives 6-12 on the Fabric B they will still be able to communicate with the picker which is drive 1. I was just under the impression that drive 1 has to be in both fabrics, but if it doesnt then Im all set.

side note, should I create a vsan just for tape backup or keep everything in one vsan ?

[dynamoxxx]

so commvault server will have two HBAs, one in fabric A zonned to picker and drive 1-6 and second HBA in fabric B zonned to drives 7-15 ?

I like to keep my tape traffic segregated from my disk traffic, that applies that if your commvault server will need SAN storage that will require yet another set of HBAs for "disk" VSAN. It's always good practice not to mix disk and tape traffic on the same HBA/port.

@dynamoxxx

[anton.mssm]

yes I will have two HBAs in the server one will be for tape traffic and other for disk luns.

[Steven.langdale_2]

As has been stated, a seperate VSAN is a good way to go.

Whilst your proposed config is valid, i'm not sure there is much benefit in doing it.  As you only have one control path, the switch thats is on is a single point of failure. so spreading tapes across 2 Fabrics gains no added resilliance.

All it does gain in that all your hosts that need tape access will need twice as many HBA's.

If you can configure your libray to have multiple control paths (lots can) AND your backp S/W supports it, then it may be a good config to go for.

FWIW, unless I have an environment where it is CRITICAL that the backup system is always available (not often), I'll put all drives on a single fabric.  with enough HBA's on the tape clients to get the required bandwidth.

Steven

[dynamoxxx]

we need to make that distinction who will be using the tape drives, if tapes drives will be exclusively used by the backup server than it makes perfect sense to spread them over multiple fabrics. Yes you have SPOF in your library, that's regardless if you put it on one fabric or multiple. Any decent size backup server will have multiple HBAs to keep LTO5 and LTO6 drives busy so why not spread over multiple fabrics.

@dynamoxxx

[anton.mssm]

So I 5 servers that all do backup to san disk (netapp) and also do tape drive backups (ndmp and non-ndmp)

Each server has 2 HBA's one will be going to fabirc A and the other fabric B. Backups run 24/7 they never stop there is so much data. The goal is to load balance the traffic and improve performance, so I guess thats why I want to spread them over two fabrics I hope that makes sense.  I was just concerned that I wouldnt be able to do it if I have the library controller seperate from other drives

[Steven.langdale_2]

True you have an SPOF with the library, but currently the switch that connectes to the control path is also an SPOF, so adding another switch will not add resilliance (one of the main reasons for dual fabrics)

The other downside (as I see it) is that most tape drivers enable you to use alternate pathing, incase you loose an fc adapter on the backup server.  Spreading them across 2 fabrics means more HBA's in the backup server to accomdate this.

So more HBA's and possibly more switches (though id doesn't look like it in this instance), and another VSAN to manage, all for what benefit?

Steven

[dynamoxxx]

resiliency no, load-balancing yes. Dedicated "tape" vsan on each fabric, where VSAN members will be your backup server HBA, tape drives ..and maybe HBAs from servers that will be doing LAN-Free backups.

@dynamoxxx

[anton.mssm]

thank you both for your help, this forum is great, the feedback here if fast and folks know their stuff. cheers.