GFS over GNBD servers connected to a SAN?

[Gary Shi <garyshi@xxxxxxxxx>]

The Administrator's Guide suggests 3 kinds of configurations, the
second one "GFS and GNBD with a SAN", servers running GFS share device
export by GNBD servers. I'm wondering the detail of such configuration.
Does it have better performance because it could distribute the load on
single GNBD servers? Compared to the 3rd way, "GFS and GNBD with
Directly Connected Storage", seems the only difference is we could
export the same device through different GNBD servers. Is it true? For example:

Suppose the SAN exports only 1 logical device, and we have 4 GNBD
servers connect to the SAN, and 32 application servers share the
filesystem via GFS. So the disk on SAN is /dev/sdb on each GNBD server.
Can we use "gnbd_export -d /dev/sdb -e test" to export the device a
same name "test" on all GNBD servers, make every 8 GFS servers share a
GNBD server, and the total 32 GFS nodes finally access the same SAN
device?

What configuration is suggested for a high-performance GNBD server? How many client is fair for a GNBD server?

BTW, is it possible to run NFS service on GFS nodes, and make different
client groups access different NFS servers, resulting in a lot of NFS
clients access a same shared filesystem?

-- 
regards,
Gary Shi
--

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