repartitioning software raid1 -- remotely?

[Will Trillich <will@serensoft.com>]

short version: how to repartition a software raid 1 (mirroring)
remotely?

long version:

so the client (hundreds of miles away) has a fresh debian woody
running on a software raid1 (mirroring) setup. but the
partitioning needs an overhaul:

Filesystem  1k-blocks      Used Available Use% Mounted on
/dev/md1     72090640    541412  68619620   1% /
/dev/md2      3747472    212280   3382904   6% /var
/dev/md0        93207      5344     84013   6% /boot

yikes!

so i (in indiana) am thinking i can
- split the raid (in boston) back into two hd* drives,
- repartition the non-booted one,
- shuffle stuff over to the new partitions,
- reconfigure lilo,
- boot from the newly-partitioned drive,
- repartition the first drive to match the booted one,
- re-establish raid parameters,
- lilo some more,
- and then reboot again.

is that a sane/possible approach?

since we're NOT anywhere near the client machine, this seems to
be a reasonable way of repartitioning the thing, remotely. if
not, other pointers welcome.

so how do we split the raid up without borking the remote
computer into a non-bootable/non-reachable state?



<dmesg snippet="in case it helps">
VFS: Mounted root (cramfs filesystem).
Freeing unused kernel memory: 128k freed
md: md driver 0.90.0 MAX_MD_DEVS=256, MD_SB_DISKS=27
 [events: 00000014]
 [events: 00000014]
md: autorun ...
md: considering hdb3 ...
md:  adding hdb3 ...
md:  adding hda3 ...
md: created md1
md: bind<hda3,1>
md: bind<hdb3,2>
md: running: <hdb3><hda3>
md: hdb3's event counter: 00000014
md: hda3's event counter: 00000014
md: RAID level 1 does not need chunksize! Continuing anyway.
md: raid1 personality registered as nr 3
md1: max total readahead window set to 124k
md1: 1 data-disks, max readahead per data-disk: 124k
raid1: device hdb3 operational as mirror 1
raid1: device hda3 operational as mirror 0
raid1: raid set md1 active with 2 out of 2 mirrors
md: updating md1 RAID superblock on device
md: hdb3 [events: 00000015]<6>(write) hdb3's sb offset: 73240256
md: hda3 [events: 00000015]<6>(write) hda3's sb offset: 73240256
md: ... autorun DONE.
Adding Swap: 979956k swap-space (priority -1)
</snip>

-- 
I use Debian/GNU Linux version 3.0;
Linux boss 2.4.18-bf2.4 #1 Son Apr 14 09:53:28 CEST 2002 i586 unknown
 
DEBIAN NEWBIE TIP #109 from Dave Thayer <dave@thayer-boyle.com>
:
Puzzled about HOW TO READ COMPRESSED FILES? In /usr/share/doc
there are tons of *.gz files -- they're "gzipped" to save space.
I like to use lynx to read the stuff in /usr/share/doc/*. It
handles gzip textfiles just fine and makes it easy to navigate
between files.  If there is HTML documentation you can follow
the hyperlinks.
  BTW, if you install the doc-linux-html package you get the
HOWTOs in hypertext.

Also see http://newbieDoc.sourceForge.net/ ...