Re: HA with qlogic FC and linux raid

[Steven Dake <sdake@mvista.com>]

Do you see an OOPS when one of the paths of the multipath leaves, or 
only when all paths are dead or in LIP.

Thanks
-steve

frank@behner.org wrote:

>Hi,
>
>We try to build a HA environment for a Document Management System. Before I come
>to the problem I will briefly describe our setup. We have two buildings and a
>fibrechannel switch in each building and attached to it a disk arrays, a DB
>server for the metadata (Linux with Oracle) and a fileserver under W2K for the
>bulk data. The fileserver runs under W2K, because the application server runs
>under W2K. The servers are also connected to the switch in the other building.
>The idea is to mirror the data over the buildings. All machines are connected
>with two fibres (using QLA2202F cards) to each switch. Also the arrays are using
>two connections to the switch. is true for. So we have a multiple pathes from
>the machines to the arrays.
>
>The Linux machines are using md-raidtools to mirror over the buildings. To see
>the correct number of devices we have used first the failover qlogic driver 6.01
>and afterwards the standard version upto 6.04beta4 with the multipath
>personality of the mdtools.
>
>The system runs till we need the failover. But if pathes are not available we
>get a kernel Oops in the RAID1 personality of the md and any IO to the disk
>arrays hangs forever, the machine does also not shutdown correctly. Because we
>see this behaviour also if a windows machine boots and sends a LIP reset over
>the fibre channel, this is even for normal operations not acceptable. Needless
>to say that the W2K do not have this problem. Therefore we concluded that the
>setup of the hardware is ok,(BIOS settings are the same for Linux and W2K). Of
>course we are unsure whether the problem is in the mdtools or in the qlogic
>driver (who should handle the LIP reset). We try to get help from Linux
>companies, but we where not very successful.I could send the list Oops and more
>information if it would help. Maybe it is well known problem having a raid1
>personality over two multipath personalities. (The Oops says something from a
>NULL pointer which he can't follow and if I understood it correctly, it happens
>after all pathes are gone, due to LIP reset). The LIP reset problem was first
>seen while the mirror was resyncing and a windows machine got rebooted.
>
>Thank you for some feedback
>     Frank Behner
>
>
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