LVM and VxVM

How to use more than 1 fiber controller simultaneously?

 
Bernie Vande Griend
Respected Contributor

How to use more than 1 fiber controller simultaneously?

We have several HP-UX 11i systems with 2 A5158A fiber cards in them connected to a brocade switch and then a Hitachi SAN. If you look at the volume groups you see one both paths listed with 1 as an alternate. On most systems the same path is the primary which tells me we are only using one controller actively. I know I can switch the path for a volume group using vgreduce and that may help on systems with multiple physical SAN devices but it won't be very balanced. ANother idea is to allocate multiple devices from the SAN and stripe the logical volumes across both paths. I'm looking for any ideas on this and for more information if anyone is doing the logical volume striping across fiber cards and how they are doing it. Also, I'm looking for ideas on how to move the current environment to a striped one without a restore. Could this be moved over with mirroring and physical volume groups somehow. I also have heard of a Secure Path product but I'm not sure if that is an option here. Any ideas/feedback on any of this is welcome.
Ye who thinks he has a lot to say, probably shouldn't.
6 REPLIES 6
RAC_1
Honored Contributor

Re: How to use more than 1 fiber controller simultaneously?

If you are already doing stripping on SAN, I wont go for doing it at OS level. The alternate paths are not really for load balancing, but are for fallback.

But for FS, which has say 4 pvs, I would route two from one controller and other two from different controller. For doing load balancing, you need a product as secure path. Veritas VxVM does DMP-Dynamic Multiple pathing.

Anil
There is no substitute to HARDWORK
harry d brown jr
Honored Contributor

Re: How to use more than 1 fiber controller simultaneously?

Let's say I have four disks on fibre_channel_A:
c0t6d0, c0t6d1, c0t6d2 and c0t6d3.

Let's also say I have an alternate path to the same disks, and their names are:
c1t6d0, c1t6d1, c1t6d2 and c1t6d3.

I would then create the VG, alternating the PV names, thus the primaries would be:
c0t6d0, c1t6d1, c0t6d2 and c1t6d3.

and my alternate links would be added later in this order:
c1t6d0, c0t6d1, c1t6d2 and c0t6d3.

And, yes you can do it after the fact by doing vgreduce's.

live free or die
harry
Live Free or Die
Bernie Vande Griend
Respected Contributor

Re: How to use more than 1 fiber controller simultaneously?

Thanks guys. I knew how to do that with multiple PVs and have done that but I was looking for other ideas on how to best utilize multiple fiber cards without an additional product like Secure Path.
Also, does anyone have a methode for checking the utilization of the fiber cards themselves and proving that they are being maxed out? Glance/Measureware are showing the IO of the device, but that doesn't necesarily show where the limit is.
Ye who thinks he has a lot to say, probably shouldn't.
RAC_1
Honored Contributor

Re: How to use more than 1 fiber controller simultaneously?

You can check the statics of the FCs.

fcmsutil /dev/tdx stat and lot of other options.

Anil
There is no substitute to HARDWORK
Bernie Vande Griend
Respected Contributor

Re: How to use more than 1 fiber controller simultaneously?

fcmsutil /dev/tdx stat does give a lot of information, but I'm not seeing a way to tell the utilization of the card from that. What specifically should I be looking at in that output or is there any option like devstat that would give me what I need? Thanks!
Ye who thinks he has a lot to say, probably shouldn't.
RAC_1
Honored Contributor

Re: How to use more than 1 fiber controller simultaneously?

I think a closer look at the man page of fcmsutil should give what you want. I think you want to know the throughput of FC cards. Right??

On arryas like VA7400, there SDM commands related to this. Those like armperf and related arm* commands. Those give a lot of information on how FCs are performing.

Anil
There is no substitute to HARDWORK