On Sat, Sep 11, 2004 at 11:42:42AM -0700, shane stixrud org wrote: > It seems that with mdadm I must create software raid partitions and > then configure mdadm for multiple paths, which sounds like it would be > functional for partitions other than /boot. actually that's not the case; you don't need to make special software raid partitions > RDAC behaves like a linux network bonding for SCSI/fiberchannel complete > with failover and loadbalancing :) so does mdadm (well failover) and in RHEL4 the device mapper multipathing does loadbalancing too. The big question is at what level you do multipathing, there are 3 options 1) inside the low level driver (as old qlogic drivers do) 2) inside/near the bottom of the scsi midlayer 3) on a block layer level the approach everyone seems to have agreed on (even IBM, but that was after they had some implementation already) in linux is to go for the third option. That way you can multipath scsi with non-scsi adapters as well, and in addition that's the level where all IO scheduling and grouping (eg the elevator) is happening and that is the level that is in charge of latency constraints for example.
Attachment:
pgp00007.pgp
Description: PGP signature