Re: Accessing the same disk via multiple channels

From: Bernd Eckenfels (
Date: Thu Feb 13 2003 - 17:45:51 EST

In article <> you wrote:
> Each server is equipped with 2 FibreChannel cards. The SAN is
> configured to present the same disk (which is in fact a virtual
> Symmetrix device) over two channels. This means the host sees
> two physical devices (as far as that host's concerned) which is
> in fact really only one device. In linux terms: /dev/sda and /dev/sdc
> are exactly the same disks, but the (standard) OS doesn't know this.
> How does linux as it is now handle the situation of one physical device
> presented via multiple paths (without extra software)?

You can use the multipath option to md which can do that.

Basically there are two options, a failover and a load balancing option. The
problem with failover is, to detect the actual failure reliable, toe problem
with load balancing is, that not all san configurations allow this.

this is at least in 2.4.20-xfs


eckes privat -
Project Freefire -
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

This archive was generated by hypermail 2b29 : Sat Feb 15 2003 - 22:00:50 EST