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Bug 155550 - multipath -l rescans all paths
Summary: multipath -l rescans all paths
Alias: None
Product: Fedora
Classification: Fedora
Component: device-mapper-multipath
Version: rawhide
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Alasdair Kergon
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2005-04-21 12:09 UTC by Lars Marowsky-Bree
Modified: 2007-11-30 22:11 UTC (History)
6 users (show)

Fixed In Version:
Doc Type: Enhancement
Doc Text:
Clone Of:
Last Closed: 2005-05-05 21:37:47 UTC

Attachments (Terms of Use)

Description Lars Marowsky-Bree 2005-04-21 12:09:37 UTC
multipath -l rescans all physical paths; which, if a path is failing/timed out
can take quite long and gets stuck easily.

I think it would be better if it just scanned the DM multipath tables and
reported what it finds there, w/o accessing the backing devices. This would also
be much, much faster.

Comment 1 Christophe Varoqui 2005-04-22 22:34:45 UTC
I could make a "light list" option, but not rescaning all paths will trim the
output from :
- prio (not printed now actually)
- path state (according to checkers)
- h/b/t/l
- devname (/dev/sda)

Now, path_discovery() have this new flag to fetch just what is necessary.
I personnaly think the bare minimum info to output in addition to DM table and
status are h/b/t/l and devname.

I could make that the output of '-l', '-ll' adding checkers, '-lll' adding prio

What do you think ?

Comment 2 Lars Marowsky-Bree 2005-04-25 12:17:45 UTC
Well, scanning the devname doesn't require to actually _open_ the device nodes
though (and thus doesn't cause IO delays); merely stat()ing them is enough, or
even scanning /proc/partitions for the name associated with the major:minor.

h/b/t/l likewise only requires to scan sysfs, w/o needing to access the physical

And, when I'm asking for the current status, I want the kernel's view, not what
the path checker thinks ;-) (The path checker could be displayed as additional

So I think your proposal makes perfect sense.

Comment 3 Lars Marowsky-Bree 2005-04-25 12:18:26 UTC
Oh, actually: The path checker & prio status could be requested from the daemon
(if running), no?

Comment 4 Christophe Varoqui 2005-05-04 21:12:16 UTC
'-l', '-ll', as described above is merged in commit
b30da450994dc52b3db45b5268a6fb418094796b at korg.

I suggest closing this one, as prio values are only relevant as a debug info and
is available via '-v3+'. I think '-lll' is not required after all.

Comment 5 Alasdair Kergon 2005-05-05 21:41:31 UTC
Closed: using 'NEXTRELEASE' to indicate that it's resolved in multipath-tools
and will get included in Fedora next time we import your tarball.

It's still possible to continue the discussion here after it's closed, and it
can easily be re-opened if we do decide we want more changes.

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