Hot Shot

## Fibre Channel - Paths to a LUN

Hi, Could someone kindly confirm this from the vSphere Config Max document.

Is this the maximum paths to a single LUN from an ESX4 host?

If that the case a single ESX host can see max 256 LUNS

256 LUNS x 16 paths = 4096 paths, however it also state max paths per host is 1024. So if I understand correctly "Total paths on a host"

would be the limiting factor, and we can say based on the amount of paths per host that would limit the amount of LUNS it could see.

Nicholas VCP6
1 Solution

Accepted Solutions
Immortal

Usually (in switched fabric with 2 HBA for each host) the number of path for each LUN is 4.

So 256 x 4 = 1024.

You can use more HBA to have more path, but in this case I think that the number of total LUN (for each hosts) will be smaller.

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
5 Replies
Immortal

Usually (in switched fabric with 2 HBA for each host) the number of path for each LUN is 4.

So 256 x 4 = 1024.

You can use more HBA to have more path, but in this case I think that the number of total LUN (for each hosts) will be smaller.

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
Hot Shot

Thanks Andre,

I'm just going through this document to study for the VCP4 exam, are you able to explain the next two item's

LUNs concurrently opened by all virtual machines = 256

And

LUN ID = 255

Thanks Nicholas

Nicholas VCP6
Immortal

I also are study for the VCP4 exam

LUN ID start from ID 0, so the max id is 255.

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
Hot Shot

Thank's Andre,

Now I just need to find out what LUNs concurrently opened by all virtual machines means exactly.

Do you mind me asking what docs you are studying for the VCP4? I found this link quite usful. most link to VMware PDFs

Thanks

Nicholas

Nicholas VCP6
Immortal

Do you mind me asking what docs you are studying for the VCP4?

There are also some other links in VCP Community (http://communities.vmware.com/community/vmtn/certedu/certification/vcp)

Andre

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro