software raid

[C M Reinehr]

Vu,

On Thu 07 August 2008 11:11, vu pham wrote:
> Sorry for the typo, it is raid 0 not raid 5, but the same problem still
> hold.
>
> vu pham wrote:
> > My RHEL5 server has the root partition mounted on  a software raid 5 of
> > 3 disks sda, sdb and sdc. I remove one of the disks and mdadm still
> > reports everything is ok, all disks are active and sync.
> >
> > The server hardware log does show the disk is removed. ( I checked this
> > just in case I took the drive from another server ).
> >
> > Below is the output of mdadm.
> >
> > Thanks for your advice.
> >
> > Vu
> >
> >
> > [root at wks-178 ~]# mount
> > /dev/md2 on / type ext3 (rw)
> > proc on /proc type proc (rw)
> > sysfs on /sys type sysfs (rw)
> > devpts on /dev/pts type devpts (rw,gid=5,mode=620)
> > /dev/md0 on /boot type ext3 (rw)
> > tmpfs on /dev/shm type tmpfs (rw)
> > none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
> > sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
> >
> > [root at wks-178 ~]# mdadm --detail /dev/md2
> > /dev/md2:
> >         Version : 00.90.03
> >   Creation Time : Thu Aug  7 10:50:37 2008
> >      Raid Level : raid0
> >      Array Size : 421585152 (402.05 GiB 431.70 GB)
> >    Raid Devices : 3
> >   Total Devices : 3
> > Preferred Minor : 2
> >     Persistence : Superblock is persistent
> >
> >     Update Time : Thu Aug  7 10:50:37 2008
> >           State : clean
> >  Active Devices : 3
> > Working Devices : 3
> >  Failed Devices : 0
> >   Spare Devices : 0
> >
> >      Chunk Size : 256K
> >
> >            UUID : cf7cc365:fbacd375:3a623d90:e9c8d292
> >          Events : 0.1
> >
> >     Number   Major   Minor   RaidDevice State
> >        0       8        3        0      active sync   /dev/sda3
> >        1       8       19        1      active sync   /dev/sdb3
> >        2       8       35        2      active sync   /dev/sdc3
> > [root at wks-178 ~]#

This is from the mdadm manual, describing modes of operation:

Follow or Monitor 
	Monitor one or more md devices and act on any state changes. This is only
meaningful for raid1, 4, 5, 6, 10 or multipath arrays as only these have
interesting state. raid0 or linear never have missing, spare, or failed
drives, so there is nothing to monitor.

First, do you have the mdadm monitor daemon enabled and running?

Second, from the sound of it, monitoring may not work on raid 0 arrays, even 
if you have it enabled. Someone with more knowledge of mdadm will have to 
answer this.

cmr

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