enbd+raid5 problem

hi!

I am new to the mailing list and have a problem with enbd+raid5.
My system is debian sarge kernel 2.6.8-2-smp on all clients and servers.
I have 4 enbd-server providing 4 devices for enbd. (backened1, backend2
backend3, backend4)

On the client side I mount 4 devices (/dev/nda,/dev/ndb,/dev/ndc,/dev/ndd)
which works quite fine I guess. Here is the output of /proc/nbdinfo:
Device a:       Open
[a] State:      verify, rw, enabled, validated, show_errs, last error 0,
lives 5, bp 0
[a] Queued:     +0R/0W curr (check 0R/0W) +252R/1W max
[a] Buffersize: 262144  (sectors=512, blocks=64)
[a] Blocksize:  4096    (log=12)
[a] Size:       2008092KB
[a] Blocks:     502023
[a] Sockets:    2       (*)     (+)
[a] Requested:  490.28K (245K)  (245K)  490.2KR/5W      max 1
[a] Despatched: 490.28K (245K)  (245K)  490.2KR/5W      md5 0W (0 eq, 0 ne,
0 dn)
[a] Errored:    3       (0)     (0)     0+3
[a] Pending:    0       (0)     (0)     0R/0W+0R/0W
[a] B/s now:    0       (0R+0W)
[a] B/s ave:    216K    (216KR+0W)
[a] B/s max:    2.79G   (2.78GR+4.88MW)
[a] Spectrum:   99%1
[a] Kthreads:   0       (0 waiting/0 running/2 max)
[a] Cthreads:   2       (+)     (+)
[a] Cpids:      2       (7029)  (7030)
Device b:       Open
[b] State:      verify, rw, enabled, validated, show_errs, last error 0,
lives 5, bp 0
[b] Queued:     +0R/0W curr (check 0R/0W) +252R/1W max
[b] Buffersize: 262144  (sectors=512, blocks=64)
[b] Blocksize:  4096    (log=12)
[b] Size:       2008092KB
[b] Blocks:     502023
[b] Sockets:    2       (+)     (*)
[b] Requested:  490.28K (245K)  (245K)  490.2KR/4W      max 1
[b] Despatched: 490.28K (245K)  (245K)  490.2KR/4W      md5 0W (0 eq, 0 ne,
0 dn)
[b] Errored:    3       (0)     (0)     0+3
[b] Pending:    0       (0)     (0)     0R/0W+0R/0W
[b] B/s now:    0       (0R+0W)
[b] B/s ave:    216K    (216KR+0W)
[b] B/s max:    2.79G   (2.79GR+3.90MW)
[b] Spectrum:   99%1
[b] Kthreads:   0       (0 waiting/0 running/2 max)
[b] Cthreads:   2       (+)     (+)
[b] Cpids:      2       (7033)  (7034)
Device c:       Open
[c] State:      verify, rw, enabled, validated, show_errs, last error 0,
lives 5, bp 0
[c] Queued:     +0R/0W curr (check 0R/0W) +20R/157W max
[c] Buffersize: 262144  (sectors=512, blocks=64)
[c] Blocksize:  4096    (log=12)
[c] Size:       2008092KB
[c] Blocks:     502023
[c] Sockets:    2       (+)     (*)
[c] Requested:  490.26K (245K)  (245K)  29R/490.2KW     max 1
[c] Despatched: 490.26K (245K)  (245K)  29R/490.2KW     md5 137KW (133K eq,
3.88K ne, 0 dn)
[c] Errored:    0       (0)     (0)     0+0
[c] Pending:    0       (0)     (0)     0R/0W+0R/0W
[c] B/s now:    0       (0R+0W)
[c] B/s ave:    216K    (0R+216KW)
[c] B/s max:    3.10G   (109MR+2.99GW)
[c] Spectrum:   99%1
[c] Kthreads:   0       (0 waiting/0 running/1 max)
[c] Cthreads:   2       (+)     (+)
[c] Cpids:      2       (7031)  (7032)
Device d:       Open
[d] State:      verify, rw, enabled, validated, show_errs, last error 0,
lives 6, bp 0
[d] Queued:     +0R/0W curr (check 0R/0W) +1R/1W max
[d] Buffersize: 262144  (sectors=512, blocks=64)
[d] Blocksize:  4096    (log=12)
[d] Size:       2008092KB
[d] Blocks:     502023
[d] Sockets:    2       (+)     (*)
[d] Requested:  9       (3)     (6)     9R/0W   max 1
[d] Despatched: 9       (3)     (6)     9R/0W   md5 0W (0 eq, 0 ne, 0 dn)
[d] Errored:    0       (0)     (0)     0+0
[d] Pending:    0       (0)     (0)     0R/0W+0R/0W
[d] B/s now:    0       (0R+0W)
[d] B/s ave:    0       (0R+0W)
[d] B/s max:    8.78M   (8.78MR+0W)
[d] Spectrum:   40%0    60%1
[d] Kthreads:   0       (0 waiting/0 running/1 max)
[d] Cthreads:   2       (+)     (+)
[d] Cpids:      2       (7035)  (7036)
Device e-p:     Closed

On top of the enbd-devices I try to run raid5 using mdadm:

mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/nda /dev/ndb
/dev/ndc /dev/ndd

The array is build and shows following output:

Personalities : [raid5]
md0 : active raid5 nda[0] ndc[2] ndb[1] ndd[3]
      4016000 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

The problem starts when I remove one enbd-server. The raid array does not
recognize that one device is missing and still marks all devices online!!
I am using the raid module provided by the kernel. Do I have to compile a
new kernel with another raid module?


Did anybody have the same problem already? I could´nt find it anywhere...


Thanks,

Chris