topic Re: existing LUNs get disconnected when new LUN is presented in Operating System - Linux

existing LUNs get disconnected when new LUN is presented

glennn — Fri, 19 Nov 2010 06:14:55 GMT

Hi.

i have a bunch of linux servers (SLES9 SP4) and are virtually identical in terms of hw/sw SAN components (i.e. qlogic, module config, driver/firmware version, multipathd config and such).

I noticed that one of those servers disconnect currently mounted LUNs whenever a new LUN is presented to it. I haven't even did a rescan of the scsi bus yet, just presented the vdisk in the array w/c is an eva6100. I've checked the switches and the EVA and i found nothing that could point to a problem.

i'm thinking i bumped into a multipathd bug.

sw verions:

host010:~ # uname -r; rpm -qa | grep multipath; grep qla /etc/modprobe.conf.local
2.6.5-7.317-smp
multipath-tools-0.4.7-75.7
options qla2xxx ql2xmaxqdepth=16 qlport_down_retry=64 ql2xloginretrycount=16 ql2xfailover=0 ql2xlbType=0 ql2xautorestore=0x0 ConfigRequired=0
remove qla2xxx /sbin/modprobe -r --first-time --ignore-remove qla2xxx && { /sbin/modprobe -r --ignore-remove qla2xxx_conf; }

thanks!

Re: existing LUNs get disconnected when new LUN is presented

TwoProc — Mon, 22 Nov 2010 23:35:06 GMT

My guess is a) too many devices. In Linux systems, there are limits to how many devices you can have. At one time it was 256, but since then, I believe "they" have increased it.
My b) other guess is that you're using a big zone for all of this stuff instead of creating nice clean small zones for certain cards on your server to get certain cards on your storage system.

If you letting multiple hosts see multiple devices in the *same* zone, you can start to see all sorts of crazy stuff, kinda like what you're seeing.

Re: existing LUNs get disconnected when new LUN is presented

glennn — Tue, 23 Nov 2010 03:26:02 GMT

Nope. i only have less than 20 LUNs presented to the said server. As for zoning configurations, only that server sees those LUNs.