On Tue, Mar 17, 2009 at 12:32 PM, Kris Buelens <[email protected]> wrote: > XLINK makes it possible to protect multiple minidisks on a shared > pack. XLINK checks cylinder ranges.
Incorrect Kris. XLINK only protects the starting cylinder. However, as long as "magic" ensures identical directories, this should be a moot point. > You can test this > - on VMA, use LINK userid vdev 1 M > - on VMB try LINK userid vdev 1 M > and this should fail, CP should tell "userid vdev not linked, R/W by VMA" > Note that there are no commands to dynamically the XLINK definitions > as those found in SYSTEM CONFIG, and IPL is required. > > You don't need to define the volumes as shared, but BEWARE: > - The problem is MDC: when MDC is active for a volume, CP may find > request data in storage > and may no go to the disk fo satisfy an I/O. Hence is an update > took place in VMA This risk there is when volumes are dynamically added to the sytem, they are per default eligable for MDC. So to play safe you should set MDC OFF if you care a bit about your data. I recall that Perry did some work in the ancient past to do the MDC ON/OFF via ISFC. Berry is looking at Linux disks. In that case there is no legitimate reason to have users read and write at the same time. A few MDC FLUSH in the PROFILE EXEC might be good enough to wipe out trails of a previous incarnation. Bonus points for using PROP to capture the logoff and flush the disks... Rob
