SAN Planning Question

[dap]

The LUNS are our SAN are 465GB. I have some questions about moving forward.

1. How may hosts should I have connected to 1 LUN

Is it better to have two hosts connected to 1 LUN vs four hosts connected to 2 LUNS

2. How many servers are typically in your HA/DRS pools.

[jjohnston1127]

If you ever want to VMotion between ESX servers then each host has to be able to see each LUN that the machines are stored on. As far as recommended numbers, I do not have any experience in that.

[dap]

Thanks. I am aware of the Vmotion requirement. I am trying to get ideas about how to move forward with VMware in our environment. Currently we have two servers attached to the SAN with 2 LUNS seen as 935 GB. The rest are DAS. All new VMware servers are to be connected to SAN. It seems like we will end up with each dept purchasing their own VMware servers(long story).

Should I purchase two at a time , assign a LUN or two and put them in their own HA/DRS pool.

Thanks

[jjohnston1127]

The ESX installs I have done have not totaled more than 4 ESX hosts, but I have configured one HA/DRS pool and presented up to 6 LUNS per ESX host without any problems experienced so far.

I'm not sure if there is any performance degradation for presenting multiple LUNs to an ESX host. What has to be watched is the amount of VMs running on a particular LUN as far as disk performance is concerned.

Again, this is just me talking from personal experience and opinion so you might want to wait from an official answer from one of the gurus here. I'm sure eseibert will post some links as soon as he sees this

[Texiwill · Accepted solution]

Hello,

There is a logical limit on the # hosts that should see a single LUN and that is determined by the SAN. Generally it is either no more than 8 (safe bet) or 16 (risky).... Too many hosts connected and you will see SCSI REservation Conflicts.

I tend to limit my # of Servers that see any given LUN to 8 to be sure.

HA/DRS can be any number. There is no limit I know about on it, generally clusters are broken up into logical groupings more than LUNs.

I would also have at least 2 LUNs be ESX server and have all servers see those LUNs if you have 8 or less servers. If there was > 8 I may just limit which servers can see what based on SCSI Reservation Conflicts.

Best regards,

Edward