Creating degraded RAID1 w/ missingindex >=1 gives kernel error

Hi!

First of all: many thanks for the great system you've been developing.
I'm finding it very smooth to work with. Really easy to do what I want,
without any fuss.

However, there's just this little problem I encountered ;-)

Using evms 2.5.5, creating a degraded RAID1 with the default
missing-disk-index = 0 works fine.

However, with missing-disk-index = 1 (and probably higher), the kernel
refuses to start the md device, producing a "COMPLETE RAID STATE
PRINTOUT".

This printout seems to give a clue about the cause: evms always sets
(or leaves?) the devnumber and raiddisknumber for the missing disk to
zero.

Correct RAID1 with missing-disk-index = 0:
md:     L1 S00409536 ND:2 RD:2 md3 LO:0 CS:0
md:     UT:45ad5abe ST:0 AD:1 WD:1 FD:1 SD:0 CSUM:98230de5 E:00000003
     D  0:  DISK<N:0,[dev 00:00](0,0),R:0,S:1>
     D  1:  DISK<N:1,[dev fe:06](254,6),R:1,S:6>

Problematic RAID1 with missing-disk-index = 1:
md:     L1 S00240832 ND:1 RD:2 md4 LO:0 CS:0
md:     UT:45ad5b94 ST:1 AD:1 WD:1 FD:0 SD:0 CSUM:4d66c907 E:00000002
     D  0:  DISK<N:0,[dev fe:0b](254,11),R:0,S:6>
     D  1:  DISK<N:0,[dev 00:00](0,0),R:0,S:9>
                 ----                 ----

For reference: mdadm-created RAID1 with missing-disk-index = 1:
md:     L1 S00305088 ND:2 RD:2 md1 LO:0 CS:0
md:     UT:45ad3286 ST:0 AD:1 WD:1 FD:1 SD:0 CSUM:5bf0990d E:00000005
     D  0:  DISK<N:0,[dev fe:07](254,7),R:0,S:6>
     D  1:  DISK<N:1,[dev 00:00](0,0),R:1,S:1>


Just before that printout, the kernel (2.4.34) says:
md4: kicking faulty [dev fe:0b]!
(after which the array has no disks left at all and cannot start.)

>From a quick study, it seems that the kernel may actually want to kick
[dev 00:00], but fails to because it references back and forth via
either N:0 or R:0 -- which of course won't work when there are two lines
that have identical numbers...

In case someone has a fix for this, I'll probably only be able to test it
within the next 24 (maybe 48) hours; after that, playtime is over and the
system is scheduled to go live.


Then secondly, I'd like to request some way to create a _multiply_
degraded RAID1 array, i.e. with multiple missing disks. This is trivial
with mdadm, but (at least) evmsgui doesn't seem to allow it. Since
hot-adding a third or fourth disk to an LVM-ized and mounted RAID1 is
impossible, it makes much sense to me to reserve some superblock entries
for future expansion.


Best regards, and keep up the good work,

  Anne Bezemer

(Oh, and I'm not subscribed - please Cc: me when replying)


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