topic Re: Max number of luns supported in Operating System - Linux

Max number of luns supported

Wagner_17 — Fri, 22 Oct 2004 15:14:08 GMT

Dear friends,

I need to know how the max. number of luns currently supported by Red Hat Enterprise Linux ES 2.1 Standard Edition. A friend tell me 128 luns. Is this information correct?

Thanks

Wagner

Re: Max number of luns supported

Steven E. Protter — Fri, 22 Oct 2004 16:17:51 GMT

I believe that information is correct. It can however be dependent on how many luns your fiber card supports. For example certain HP fiber cards only support 8 luns on non-HP disk arrays.

SEP

Re: Max number of luns supported

Uwe Zessin — Sun, 24 Oct 2004 00:55:14 GMT

That is one part of the story. The other one is that _each_ path to a LUN on a storage array also counts against that limit. In the case of an EVA, if you have 4 paths and 3 virtual disks presented it means you deal with 12 LUNs.

Re: Max number of luns supported

xyko_1 — Tue, 26 Oct 2004 08:26:17 GMT

Wagner,

you have to pay attention also in a feature called multi_lun_support.

The default kernel does not support multi_lun, so, you have to rebuild the kernel including it.

menuconfig => SCSI Support => Probe all LUNs on each SCSI device

You may also increase the number of supported luns on the same place (SCSI Support).

But ,in general, multi_lun_support is only needed for devices like CD jukebox, LTO libraries and things like that.

Regards,
Xyko