[olug] MAX_LUNS: Caveat about selling Linux for SAN to "the management"

[Christopher Cashell]

At Wed, 17 Jan 07, Unidentified Flying Banana swanpoint, said:
> If you plan to implement Symmetrix, CLARiiON, iSCSI, or any other tech 
> that could make use of LUN greater than 255; be aware that Linux won't 
> recognize a LUN higher than 255 (but AIX, HPUX, and Windows do). Be sure 
> you don't go out and buy a ton of DL585's, DL380's, Dell 1955's, HP 
> BL45p's, and stacks of QLogic and Emulex cards and hope it works cuz' it 
> don't...

I can't help but think this sounds a little bit over the top and like
the knee-jerk response of frustration.  Are you actually dealing with a
situation where a 255 LUN limit is causing you problems?  I've been
using Linux with various SANs for quite a while, including some fairly
decent sized setups, and it's never been an issue.

The issue I've had a lot more trouble with is running out of raw
devices, specifically on Oracle RAC configurations using pre-2.6.x
kernels (max of 255 raw devices).  Honestly, I'm having trouble coming
up with much in the way of realistic situations where I would anticipate
a problem with the LUN limit, at least outside of very rare and unusual
configurations.

Can you detail your setup and where exactly the problem is coming in?

-- 
| Christopher
+------------------------------------------------+
| Here I stand.  I can do no other.              |
+------------------------------------------------+