On Wednesday 10 September 2008, Mark Hahn wrote: > >> active/active seems strange to me - it implies that the bottleneck > >> is the OSS (OST server), rather than the disk itself. and a/a means > >> each OSS has to do more locking for the shared disk, which would seem > >> to make the problem worse... > > > > No, you can do active/active with several systems > > > > Raid1 > > / \ > > OSS1 OSS2 > > \ / > > Raid2 > > > > > > (Raid1 and Raid2 are hardware raid systems). > > > > Now OSS1 will primarily serve Raid1 and OSS2 will primarily serve Raid2. > > So > > yes, I know - that's how HP SFS is set up. the OP was talking > active-active, though, meaning that IO at any instant can go to either OSS > and still make it onto a particular raid. otherwise it's active/passive, > what SFS does.
I have a real hard time understanding how lustre could manage an active/active OST. This based on the fact that an OST is essentially a ldiskfs(ext4) filesystem on a device and this setup does not work in a situation where more than one entity modifies the data. I think that what the lustre manual is refering to is a setup with two OSTs on a pair of servers. In this config one server would be active for one OST and passive for the other (and vice versa). /Peter
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