Potential issues with this connection option

[dynamoxxx]

Hello guys,

I have a tape library that is located on campus but only connected to one FC switch.  I have two redundant links to the switch and would like to load balance the load as much as possible. Does my layout look reasonable ?  I hate connecting one switch to both Fabric A and Fabric B ..but that's all i have to work with.  What's the worth that could happen ? Let's say 9134 melts down and loses its configuration ..fabric A and fabric B should not have issues because VSANs are unique on each fabric.

[Steven.langdale_2]

Is ther any reason you have to have both VSAN's at the remote point? 

Maybe it's just me being paranoid and showing my non-Cisco SAN roots, but personally I'd get 2 switches OR only extend one VSAN.

Steven

[dynamoxxx]

Steven,

no money in the budget to get another switch so i am stuck with one for now.  On 9513 i have a backup server with two HBAs ..one in fabric A and one in fabric B. I want to utilize both links to the tape library connected to 9134.

Thanks

[Steven.langdale_2]

Whilst it would be good to utilise both backup server HBA's do you need the throughput?  how big is the remote library drive wise?

Purely out of interest, whats your backup software?

Steven

[dynamoxxx]

Steven,

oh yeah, i will need the throughput. I am doing NDMP backups from Celerra to the tape library. The tape library is actually EMC EDL 4100 disk library. We are using TSM as our backup application.

[hershal06]

The worst thing I see happening if the 9134 went down hard you would have both VSANs during reconfigures or rebuilds on the 9513s at the same time. Which I suppose could ultimately affect hosts connected to those VSANs. Where if it was just 1 VSAN on the 9134 you wouldn't have that chance to affect both paths connections to a server.

Not sure what process would happen in this situation, a rebuild or reconfigure. One I believe is disruptive. Do you know which one would take place in the situation? I always seem to forget, I'll check some of notes to see if I have it written down.

[dynamoxxx]

if 9134 goes away i see how my host will lose connectivity to it but i don't see how it's going to cause problems in those VSANs.  I am sure there will be a fabric event when that switch goes away but it should be no different when i add new switches to the fabric. I've never had issues when i introduce new switch to the fabric and merge VSANs.

[Steven.langdale_2]

I don't think the switch going away would be a problem.

I the most likely cause of an issue would be an inadvertant config change on it that affects both 9513's.

As long as you're extra carefull when changing stuff on that switch (or make it a point not to make changes on it that can be done elsewhere) then it should work fine.

I'm sure you've tried your hardest to get another switch, but it suprises me that organisations are willing to "save" on a few K for a little switch when we are talking about arguably their most important asset, their data.

Steven

As an aside, are the NDMP backups going direct to this library or are they hitting TSM and then offsite copies?

[dynamoxxx]

NDMP backups are going to directly to the library over FC,  while meta data goes over IP to TSM server.

[blueyonderguy]

do you have separate FC port/HBA for the backup on host (dual channeled)? if so, you can keep your SAN traffic and backup traffic on different VSANs. Only backup VSAN would span across switches.i.e.

Fabric A - VSAN 10 for data, VSAN 11 for backup traffic

Fabric B - VSAN 20 for data, VSAN 21 for backup traffic

9134 will have only VSAN 11 and 21 configured. ISL between Fabric A and 9134 will allow only VSAN 11 and ISL between Fabric B and 9134 will allow only VSAN 21

Even otherwise, your approach seems best in the situation, to me. Just make sure that you configure ISLs and restrict VSANs across. Preferably layout your ports on 9134 such that fabric A and B do not get mixed up between ports groups (even though 9134 ports operate at line rate). This helps to logically keep things separate.

[dynamoxxx]

yep, the only VSANs that will be "trunk allow" to 9134 are the two backup VSANs (10 and 20).