[Beowulf] Lustre failover

[Mark Hahn]

>> 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.