topic Re: multipathing problem in Operating System - Linux

multipathing problem

ats1 — Fri, 22 Oct 2010 06:09:07 GMT

hi all
I installed the MPIO (multipathing) on my server (DL380G2 linux Rehat 5) and when the system reboot, there is a synchronisation problem beteewn disks and cache. After that the server crashed.
help me please !!!

Re: multipathing problem

FLQ — Fri, 22 Oct 2010 08:12:16 GMT

Hi ats1,

can you post some logs?

Re: multipathing problem

ats1 — Fri, 22 Oct 2010 13:36:07 GMT

synchronizing scsi cache for sdaj

Re: multipathing problem

Alzhy — Fri, 22 Oct 2010 15:08:58 GMT

MPIO - do you mean multipath? It is supposedly installed by default on all RHEL 5.x releases. Or do you mena HP Devcie Mapper Multipath Kit? HPDM adds a few binaries and modifys your /etc/multipath.conf file so all of HP's StiragwWorks Arrays are supported and properly multi-pathed.

What kind of storage do you have?

Re: multipathing problem

ats1 — Fri, 22 Oct 2010 16:42:27 GMT

i already installed the multipath on my systems. but when the systems reboot i have an error message (synchronizing scsi cache for sda), after that systems crash. it's a cluster beteewn deux DL380G7 (rhel5) and MSA2312i.

Re: multipathing problem

Alzhy — Fri, 22 Oct 2010 17:38:11 GMT

Very strange then.

What PSP are you using? PSP 8.5 or the 8.6? I had a tester Proliant DL 580 G7 and was on PSP 8.5 hooked up to HP StorageWorks arrays -- EVAs and XP (not MSA though). RHEL 5.5 was what I used and HPDM 4.4.1 (HP device multipather kit). Everything was just fine and dandy. Even broke all of my past SwingBench TPC records.

Re: multipathing problem

Brendan Murphy_5 — Sat, 23 Oct 2010 15:49:15 GMT

As I understand it RHEL5.2 & below requires installation of the HPDM multipath kit. Anything above that does not require HPDM kit (in fact even though it works, I don't think its supported). just make sure the correct RHEL rpm packages are selected. ... Since this is a DL380G2, you need to also ensure that the /dev/cciss devices are blacklisted in the /etc/multipath.conf file...

similar to

blacklist {
...
devnode "^cciss[!]c[0-9]+d[0-9]+"
...
}

regards,

Brendan

Re: multipathing problem

Matti_Kurkela — Sun, 24 Oct 2010 11:10:29 GMT

The "target port in standby state" makes me think these LUNs are probably provided by a storage system that handles multipathing in active/passive fashion.

In this case, the correct configuration of the storage and the multipathing system on the host are very important, otherwise you might cause performance problems for all hosts using the same storage system.

The standard way for the storage system to inform the host about the active/passive state of its ports is called ALUA, or Asymmetric Logical Unit Access. But before the ALUA standard existed, there were various manufacturer-specific protocols for the same purpose. The storage system must be configured to use the same protocol as the host is expecting to see.

There are many possible multipath solutions for RHEL 5: first there is the device-mapper-multipath included in the RHEL 5 distribution, and then there are various proprietary solutions by each storage system manufacturer, e.g. PowerPath from EMC. Which multipath solution are you using, and what's the make and model of your storage?

MK