Last night I turned on multi-path support for the main NetWare file cluster. This has been a long time coming. When we upgraded the EVA3000 to an EVA6100 it gained the ability to do active/active IO on the controllers, something that the new EVA4400 can also do.
What's more, the two Windows backup-to-disk servers we've attached to the EVA4400 (and the MSA1500 for that matter) have the HP MPIO drivers installed, which are extensions of the Microsoft MPIO stack. Looking at the bandwidth chart on the fiber-channel fabric I see that these Windows servers are also doing load balancing over both of the paths. This is nifty! Also, when I last updated the XCS code on the EVA4400 both of those servers didn't even notice the controller reboots. EVEN NICER!
I want to do the same thing with NetWare. On the surface, turning on MPIO support is dead easy:
Startup.ncf file:
Tada. Reboot, present both paths in your zoning, and issue the "list failover devices" command on the console, and you'll get a list. In theory should one go away, it'll seamlessly move over to the other.
But what it won't do is load-balance. Unfortunately, the documentation on NetWare's multi-path support is rather scanty, focusing more on configuring path failover priority. The fact that the QL2X00.HAM driver itself can do it all on its own without letting NetWare know (the "allpaths" and "portnames" options tell it to not do that and let NetWare do the work) is a strong hint that MPIO is a fairly light weight protocol.
On the support forums you'll get several references to the LSIMPE.CDM file. With interesting phrases like, "that's the multipath driver", and, "Yeah, it isn't well documented." The data on the file itself is scanty, but suggestive:
What's more, the two Windows backup-to-disk servers we've attached to the EVA4400 (and the MSA1500 for that matter) have the HP MPIO drivers installed, which are extensions of the Microsoft MPIO stack. Looking at the bandwidth chart on the fiber-channel fabric I see that these Windows servers are also doing load balancing over both of the paths. This is nifty! Also, when I last updated the XCS code on the EVA4400 both of those servers didn't even notice the controller reboots. EVEN NICER!
I want to do the same thing with NetWare. On the surface, turning on MPIO support is dead easy:
Startup.ncf file:
SET MULTI-PATH SUPPORT = ON
LOAD QL2X00.HAM SLOT=10001 /LUNS /ALLPATHS /PORTNAMESTada. Reboot, present both paths in your zoning, and issue the "list failover devices" command on the console, and you'll get a list. In theory should one go away, it'll seamlessly move over to the other.
But what it won't do is load-balance. Unfortunately, the documentation on NetWare's multi-path support is rather scanty, focusing more on configuring path failover priority. The fact that the QL2X00.HAM driver itself can do it all on its own without letting NetWare know (the "allpaths" and "portnames" options tell it to not do that and let NetWare do the work) is a strong hint that MPIO is a fairly light weight protocol.
On the support forums you'll get several references to the LSIMPE.CDM file. With interesting phrases like, "that's the multipath driver", and, "Yeah, it isn't well documented." The data on the file itself is scanty, but suggestive:
LSIMPE.CDMBut the exact details of what it does remain unclear. One thing I do know, it doesn't do the load-balancing trick.
Loaded from [C:\NWSERVER\DRIVERS\] on Feb 4, 2009 3:32:13 am
(Address Space = OS)
LSI Multipath Enhancer
Version 1.02.02 September 5, 2006
Copyright 1989-2006 Novell, Inc.