Storage Maximums

[pavangogineni]

My setup is, ESX (4.1) connected to DMX assigned with 64 luns through 4 FA ports. Now I want to assign luns from different storage. Will I be able to do that or did I reached maximum number of SCSI devices (64*4=256)?

B'coz when I tried to assign luns from different storage, my host is not able to recognize those luns. Interestingly, when I removed DMX luns, all the new luns were visible.

Also I am confused with these two statements:

1) maximum number of luns - 256

2) maximum number of total paths - 1024

If I have one path to each lun, will I be able to assign 1024 luns?

[gaspipe]

Maybe you assigned the same LUN IDs for the new LUNs as you had for the old LUNs? When you removed the old LUNs, the IDs were freed and the new LUNs "became visible".

>> If I have one path to each lun, will I be able to assign 1024 luns?

No. Max is 256 LUNs, no matter how many paths you use.

[pavangogineni]

As far as I know, each lun will be recognized with some unique ID from the host. And here as I said, I am trying to connect a different storage to the server which would actually change the Target ID (in C<>T<>L<> naming). So I dont think there would be any LUN ID conflicts.

Correct me if I am wrong, I assume that each lun presented thru each path would occupy one SCSI disk number (like vmhba0:0:0:0). If the same lun is presented thru other path, it'll occupy another SCSI device ID(like vmhba1:0:0:0). As a whole ESX host can have 256 SCSI devices, I am limited to present 128 luns (assuming each one is having dual paths).

[gaspipe]

Same FC LUNs use the same runtime names (vmhbax:Cx:Tx:Lx) accross all vmhbas. This identifier is not persistent, it can change and is not a "SCSI disk number". "Fibre Channel SAN configuration guide" has all about this.

You can use no more than 256 LUNs per host no matter how many paths per LUN (if total paths on a host <=1024) and number of HBAs per host (<=8) you use. "Configuration maximums" document has more detailed information on the limits.

This is assuming you use FC storage..