inSANity

[just_al]

OK, so we have an EMC SAN that we found out a month or two ago, wasn't off-lease but actually Paid-for.  This is a good thing

Comments

[asavitzk]

Nice! And I followed it all too. :)

Have you done any research into performance differences with multiple smaller LUNs and fewer larger LUNs? I'm just unclear on what the best practices would be in this scenario:
- 1 server running VMWare ESXi with 4 iSCSI network connections
- 1 EMC SAN system with 4 iSCSI network connections
(everything is redundant)
- On the ESXi host I have 5 virtual machines and each machine needs, for argument's sake, 2 virtual hard drives.

So should I just create a single giant LUN and have ESXi manage virtual hard disk files on it or should I create 5 LUNs and have ESXi manage 2 virtual hard disk files on each LUN or should I create 10 LUNs and have ESXi manage a single virtual hard disk file per LUN?

Did some research and testing on this before :)

[asavitzk]

You want smaller luns so rebuild times won't be ghastly in case of drive failures. We had 6 drive failures and in each case you get a rebuild to bring the spare online and then another rebuild when you replace the faulty drive(they really needed a floating spare now that I think of it) :) I think the 10 Luns is the best performance options as well in terms of disk access times. We made 3 5-drive luns and bound them in a meta-lun for each database server and the performance was slightly better than the side by side disk tray on the blade servers.

-Jim

Re: Did some research and testing on this before :)

[just_al]

Exactly, rebuilding Big LUNs sucks the pole.

[just_al]

Keep in Mind, our VMware is running on full blown ESX and not ESXi