[DRBD-user] two questions about manually "drbdadm detach all"

yls yuleishou at 163.com
Thu Jan 8 16:14:33 CET 2009


Hi all,

According to the introduction at http://www.drbd.org/docs/about/, there
are two paragraphs about Diskless and detach:
    on {Disk states}: "Diskless. No local block device has been assigned
to the DRBD driver. This may mean that the resource has never attached
to its backing device, that it has been manually detached using drbdadm
detach, or that it automatically detached after a lower-level I/O
error."
   on {Disk error handling strategies}: "Masking I/O errors.  If DRBD is
configured to detach on lower-level I/O error, DRBD will do so,
automatically, upon occurrence of the first lower-level I/O error. The
I/O error is masked from upper layers while DRBD transparently fetches
the affected block from the peer node, over the network. From then
onwards, DRBD is said to operate in diskless mode, and carries out all
subsequent I/O operations, read and write, on the peer node. Performance
in this mode is inevitably expected to suffer, but the service continues
without interruption, and can be moved to the peer node in a deliberate
fashion at a convenient time."

Here are my questions:
(1) can I do maunally "drbdadm detach all" on the primary node of the
cluster? I want to simulate some kind of disk failure in this way. 
(2) if the DRBD version is 0.7.24, can I expect "From then onwards, DRBD
is said to operate in diskless mode, and carries out all subsequent I/O
operations, read and write, on the peer node. " ?? is there any
differences on this COMMAND between version 0.7.24   and 8.0/later??

thanks for help!






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