HEADS UP - devfs integration in master this weekend

Matthew Dillon dillon at apollo.backplane.com
Thu Jul 30 18:52:26 PDT 2009


:I cant wait. I think devfs is really important, with so much static nodes
:in /dev its really a mess.
:
:Just a side question, when HAMMER becomes network aware (disks
:spanning/replicating over network in a cluster), will it be possible to
:mount disks on other DragonFly servers like mount_hammer
:/dev/disk_on_the_network /mnt/mydisk and it will just know that
:disk_on_the_network is a disk on a different server that is part of the
:cluster?
:
:This will be the greatest release yet no doubt.
:
:Cheers,
:Petr

    Yes, certainly anything made available via iSCSI will be accessible
    that way even without the cluster work.  DEVFS, /etc/devtab, and
    being able to access drives by serial number is the crucial enabler.
    Antonio may disagree but I think he's close enough with his iSCSI
    port that we can finish it off next month.

    The cluster work itself will operate at and above the filesystem
    layer and is far more ambitious.  It is still at least a year away.
    Of the major components the HAMMER piece is done, and the replication
    piece has working infrastructure (HAMMER's mirroring feature).  Left
    to do is the quorum commit protocol, RPC mechanism for communication
    between nodes, and what will eventually be a very complex cache
    coherency piece.

    Without getting into too much detail, being able to extend the
    master-slave replication that HAMMER has now to master-master
    replication requires the cache coherency piece as the mechanic which
    prevents conflics in the replication streams.  With that in place
    HAMMER's mirroring feature can be used to fan-out the replication
    of changes with no topological limitations.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>





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