Re: behavior different from mdadm 2.6.4 and 3.0?

On Mon, Dec 15, 2008 at 3:11 PM, Neil Brown [off-list ref] wrote:

On Monday December 15, jnelson-linux-raid@jamponi.net wrote:

quoted

mdadm --incremental seems to behave differently for me between mdadm
2.6.4 and 3.0

With 2.6.4, mdadm --incremental /dev/nbd0 does this:

mdadm: /dev/nbd0 attached to /dev/md10 which is already active.

With 3.0, it does this:

mdadm: /dev/md10 is already in use.

and does *not* add it to the array.

Sounds like /var/run/mdadm/map is not correctly up-to-date.
Does running
  mdadm -Ir

make "mdadm -I /dev/nbd0" work properly again?

Can you provide a sequence of steps which leads to the error message
that you report?

I have to reboot to make this happen. There is probably a less
invasive way.... but it's what I know works.

First, an strace of mdadm --incremental (3.0):

turnip:~ # strace -f -e trace=open mdadm --incremental /dev/nbd0
open("/etc/ld.so.cache", O_RDONLY)      = 3
open("/lib64/libc.so.6", O_RDONLY)      = 3
open("/dev/urandom", O_RDONLY)          = 3
open("/etc/mdadm.conf", O_RDONLY)       = 3
open("/dev/nbd0", O_RDONLY|O_EXCL|O_DIRECT) = 3
open("/var/run/mdadm/map.lock", O_RDWR|O_CREAT, 0600) = 3
open("/var/run/mdadm/map", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/var/run/mdadm.map", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/var/run/mdadm/map", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/var/run/mdadm.map", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/proc/mdstat", O_RDONLY)          = 4
mdadm: /dev/md11 is already in use.
turnip:~ #


Running (again, v3.0) mdadm --incremental --rebuild-map works rebuilds the map.

Then using --incremental /dev/nbd0 works (but it's resyncing **again**).

Does that help?

Thanks,
NeilBrown

-- 
Jon