[DRBD-user] Using drbd as HA NFS Server
lllactive at gmail.com
Mon Jan 9 15:38:48 CET 2006
I have an two servers as nfs file server for other application servers.
It is like a configuration used by the SAP landscape concept, where app
servers and db servers are on separate machines. I want to separate the
data an the application servers in the network. No users should connect
to the nfs file/data server at all. The nfs file server, acting as the
data server, should be a drbd pair where the primary is mounted on
say /Data, with a GigaBit link for replication.
It should be like a NAS making the mounted /drbd0 on /Data available as
a nfs share. I have tried it thus far with the /Data mount, and it seems
to work as a share. On this /Data, there should be various directories
that can be used by various app servers like a webserver on /Data/http
and an erp server on Data/erp server and a Samba server on /Data/samba.
The directories /Data/http, /Data/erp and /Data/samba should be avaiable
via the nfs server on the drbd system to the other servers. The nfs
shares should be mounted as nfs on the respective servers with all file
and directory rights to be managed on the local server and not by the
nfs file (drbd) server. The other app servers (Web, erp & samba) should
also be pairs with heartbeat, each deriving their data from the one drbd
nfs file server.
I have read some documentation by Dave Dykstra "Setup of high
availablity NFS servers" (http://www.linux-ha.org/HaNFS)and the article
by Andre' Bonhote mentioned there
(http://www.linux-magazine.com/issue/33/High_Availability_NFS_Server.pdf). I picture the Disk-array in Figure 1 in the article as the drbd pair of servers providing the disk space, in stead of a SCSI over fibre. In effect I want to apply the configuration in Figure 1 for the application servers, just that the Disk-array is provided by the drbd pair per nfs.
My hesitation arises with the HINTS in the article:
"NFS-mounting any filesystem on your NFS servers is highly discouraged.
DaveDykstra wanted both servers to NFS-mount the replicated filesystem
from the active server, and through a lot of trouble mostly got it
working but still saw scenarios where "NFS server not responding" could
interfere with heartbeat failovers and he finally gave up on it."
Could someone make the problem perhaps clearer to a newbie please. It
seems my idea has a problem here. How could I then go about realising my
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