FibreChannel Multiple links to SAN from XenServer

[Davit2005]

My apologies if on wrong Forum, maybe a storage forum

 

We currently have VMWare for our virtual server environment but last year we had XenDesktop setup on a spare C7000 chassis with the hosts running XenServer (cost benefit).

 

At the time we only had one FlexFabric installed in the spare C7000 but when it came to adding the second FlexFabric we were advised that we might need to setup multipathing on the XenServers to make sure the host saw the multiple paths as one path, each FlexFabric has 2 Fibre connections split between 2 SAN switches (how I wish it was iSCSI, much simpler).

 

With VMWare I am pretty sure it multi-paths automatically/natively (certainly seems to when we add additional VMWare hosts and when we added the EMC storage).

 

Anyone validate we would need to setup multipathing on the XenServers. Not really sure about the nuts and bolts but can do a bit of the Fabric stuff on switches i.e. zoning etc.

 

Also if we do, I believe from what I have read that some CLI is needed on the hosts, a bit more than just a tick in a box .

 

Thanks

Edited January 30, 2015 by Davit2005

[Geoff]

Ok, you basically need multipathd running. As soon as it sees multiple block devices with the same wwid then it will muiltipath them. I have it working here on a VMware VM talking back to two NetApp Filers via iSCSI over multipath.

 

~$ sudo iscsiadm -m session
tcp: [1] 192.168.11.101:3260,2001 iqn.1992-08.com.netapp:sn.1788985965
tcp: [2] 192.168.11.103:3260,2001 iqn.1992-08.com.netapp:sn.1788985965

~$ lsscsi
[1:0:0:0]    cd/dvd  NECVMWar VMware IDE CDR10 1.00  /dev/sr0
[2:0:0:0]    disk    VMware   Virtual disk     1.0   /dev/sda
[2:0:1:0]    disk    VMware   Virtual disk     1.0   /dev/sdb
[3:0:0:0]    disk    NETAPP   LUN              811a  /dev/sdc
[4:0:0:0]    disk    NETAPP   LUN              811a  /dev/sdd

~$ sudo multipath -ll
360a980002d653732512b417146594d6b dm-4 NETAPP,LUN
size=45G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=2 status=active
 |- 3:0:0:0 sdc 8:32 active ready running
 `- 4:0:0:0 sdd 8:48 active ready running

~$ sudo file -s /dev/dm-4
/dev/dm-4: LVM2 PV (Linux Logical Volume Manager), UUID: vTQA0u-AGTu-0wsV-kLI6-k1kD-HSM0-z9vFcm, size: 4831838208

[Davit2005]

Ok, you basically need multipathd running. As soon as it sees multiple block devices with the same wwid then it will muiltipath them. I have it working here on a VMware VM talking back to two NetApp Filers via iSCSI over multipath.

 

Thanks

 

Just to confirm that we are using XenServer on these hosts and wishing to connect to the storage via Fibre Channel.

 

Our VMWare seems to sorts out the Multi-Pathing to the FibreChannel Storage by itself no intervention apart from making sure it is using the same Multi-Pathing method (i.e. Round Robin, Fixed VMWARE etc).

 

Should we be doing the same coding for FibreChannel, a few years ago I did some coding backend on VMWare for iSCSI but that was a bit different.

[Geoff]

Read this, Page 33 onwards.

 

https://support.citrix.com/servlet/KbServlet/download/33310-102-696318/xs-design-multipathing-config.pdf