[Linux-cluster] DRBD and redhat cluster
Chris Picton
lists at tangent.co.za
Sun Apr 13 16:43:05 UTC 2008
Hi all
I am planning a pair of machines using DRBD to export redundant block
devices via gnbd
I will have about 10 other machines using gfs2 to access this data.
I have thought of a few different ways of accomplishing this, and would
appreciate any feedback you may have.
I can run the drbd exports in one of three ways:
1. Single drbd device in single master mode. The drbd primary resource,
shared ip address and gndb export will fail over between the two nodes.
Advantages. Simple setup
Disadvantages. One machine always fairly idle
2. Two drbd devices on each server. Server1 will be primary on the one
device, server 2 will be primary on the other device. As above, each
drbd resource will have an associated IP address and gnbd export
associated with it. These resources will fail over between the two
nodes. The remaining cluster nodes will assemble these using a striped
clvm.
Advantages. The two nodes will be equally used. Will get double the
throughput from the pair of machines (assuming high speed bonded
crossover between the two). Also, will be able to add another pair of
these machines later to increase bandwidth and storage space for the LVM.
Disadvantages: More complex
3. A drbd device in master/master mode, exported from both via gnbd.
Cluster members will access this via dm-multipath.
Advantages: not sure
Disadvantages: Will bandwidth be shared between the two machines?
In addition to the options above, I am also wondering about the cluster
software I should use. I will have to use RHCS to use gfs2 and
fence_gnbd correctly, but is heartbeat a better choice than failover
domains for the drbd exports?
Any insight will be helpful
Chris
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