Conference spezko::cluster

5301.0. "Use Quorum VAX to check Shadowsets" by FRAIS::KHAN () Mon Apr 28 1997 12:04

    We know about this 'mounting old member' issue, if one does not wait
    for all members to be there on a cluster reboot:
    
    Two computer rooms, two systems + quorum vax. 
    One shadowset member in each location.
    
    - 1. computer room fails ... shadowset reduced to only 2.member
    - 2. computer room shutdown ...
    - cluster reboot ( 1.computer room first ) ... and the 'stale'
    shadowmember is mounted.
    
    I have thought about this and think that we could avoid this by
    mounting the shadowset on the quorum vax. This way we always know the
    status of the shadowset and hopefully the quorum vax will stop the
    'stale' (older) disk from mounting.
    
    I would like to know if this is technically correct ( code is there )!
    
    I did get a chance to try this out ( once ) and I have a feeling that
    it works. Only I would have expected an nice shad-error, but saw a
    system-w-nosuchdev. Anyway it did not mount the older member. As soon
    as the 2. (up-to-date) member came up, it got mounted. Shadow copy
    then worked for the 1.member and in the correct direction.
    
    If I donot mount the disk on the quorum vax, the older member gets
    mounted and the newer one overwritten.
    /Azfar