SAN Configuration for a new farm 3

[Stevehewitt]

Hi guys,

We have a VI3.0 farm at the moment and have recently purchased 4 new servers and 2 new SAN's along with VI3.5 to migrate / upgrade our aging farm.

Got a question about LUN's for VMWare ESX.
In a scenario with 4 hosts and approx 25-30 guests, what is a typical/recommened/suggested configuration for the LUN's on the SAN? I'm pretty new to the SAN game and need some advice as I'm a bit unsure why i'd need more than two LUN's... (one for the LAN servers, another for DMZ servers)

Cheers,




Steve.

"They have the internet on computers now!" - Homer Simpson

 

[TheLad]

It really depends on how you want the system configured. In my opinion, there is no specific reason in having a separate LUN for your LAN & DMZ servers as the VM files on the LUN don't need to be seperated despite what use the server is going to be for.

In my experience, I have seen people employ one big LUN where everything is stored (I wouldn't recommend this), separate LUNs for OS (C and Data drives (chances are the OS LUN will be more heavily utilised), and even employ RAID1 and RAID5 configs for SQL servers.

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[theravager]

Depends what you are using the guests for, if its some sort of high performance thing like 'some' sql apps then you may want to have luns for particular volumes on that server or you could group them all up on one big lun. Your security policy may require you to have different luns for dmz and internal.

There is no real right or wrong answer here.

I did note you said 2 sans, so if you are going to be doing some sort of DR replication between them you may have to design your LUNs around the replications software's requirements.

 

[unclerico]

Lad and Ravager really hit the jist of this pretty well. I'd just like to add that one of the things you'll see with huge LUN's servicing multiple VM's is LUN contention. This may be all right with servers/apps that you can tolerate a little slower response time from, but perhaps not from any of your "big" servers/apps. Also, if you get into Site Recovery Manager and you want to set up a protection group that consists of, say, 3 of the 8 VM's that are on a large datastore (LUN), your DR plan will involve replicating all VM's on that datastore as opposed to just the few that you need.

Just curious, what make/model and interconnect are they using, FC or iSCSI?? Sorry for being nosy

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[Stevehewitt]

Your welcome to be nosy!

We're using 4Gbps FC from Dell R900's to two EMC CX4 120's via two Brocade 200E FC Switches.

Hmmm, we will be using SQL, however it will really be at department level rather than anything that requires heavy performance.

Think I'll have a RAID1+0 array for SQL and the primary file server with 2 LUN's (one SQL and one File) spead across 6 disks with a total of 4 RAID5 LUN's for OS's and other servers.

Should keep things fast enough I suppose...!

Thanks to all for your advice.

Cheers,




Steve.

"They have the internet on computers now!" - Homer Simpson