Here's the output of the lvremove that hangs the machine, with debugging turned up to max. Unfortunately there is no output from the kernel.
-- Sam Morris http://robots.org.uk/ PGP key id 5EA01078 3412 EA18 1277 354B 991B C869 B219 7FDB 5EA0 1078
rescue:~# lvremove /dev/main/rootbackup Setting log/indent to 1 Setting log/prefix to Setting log/command_names to 0 Setting global/test to 0 Setting log/overwrite to 0 Setting log/file to /dev/stdout log/activation not found in config: defaulting to 0 config/config.c:778 log/activation not found in config: defaulting to 0 Logging initialised at Fri Jun 23 21:36:20 2006 commands/toolcontext.c:144 Logging initialised at Fri Jun 23 21:36:20 2006 Setting global/umask to 63 config/config.c:773 Setting global/umask to 63 Set umask to 0077 commands/toolcontext.c:163 Set umask to 0077 Setting devices/dir to /dev config/config.c:758 Setting devices/dir to /dev Setting global/proc to /proc config/config.c:758 Setting global/proc to /proc Setting global/activation to 1 config/config.c:773 Setting global/activation to 1 global/suffix not found in config: defaulting to 1 config/config.c:778 global/suffix not found in config: defaulting to 1 global/units not found in config: defaulting to h config/config.c:764 global/units not found in config: defaulting to h Matcher built with 23 dfa states regex/matcher.c:267 Matcher built with 23 dfa states Setting devices/cache to /etc/lvm/.cache config/config.c:758 Setting devices/cache to /etc/lvm/.cache Setting devices/write_cache_state to 1 config/config.c:773 Setting devices/write_cache_state to 1 Opened /etc/lvm/.cache RO device/dev-io.c:376 Opened /etc/lvm/.cache RO Closed /etc/lvm/.cache device/dev-io.c:407 Closed /etc/lvm/.cache /dev/hda1: Added to device cache device/dev-cache.c:206 /dev/hda1: Added to device cache /dev/hda2: Added to device cache device/dev-cache.c:206 /dev/hda2: Added to device cache /dev/hda3: Added to device cache device/dev-cache.c:206 /dev/hda3: Added to device cache Loaded persistent filter cache from /etc/lvm/.cache filters/filter-persistent.c:125 Loaded persistent filter cache from /etc/lvm/.cache Setting activation/reserved_stack to 256 config/config.c:773 Setting activation/reserved_stack to 256 Setting activation/reserved_memory to 8192 config/config.c:773 Setting activation/reserved_memory to 8192 Setting activation/process_priority to -18 config/config.c:773 Setting activation/process_priority to -18 Initialised format: lvm1 format1/format1.c:594 Initialised format: lvm1 Initialised format: pool format_pool/format_pool.c:360 Initialised format: pool Initialised format: lvm2 format_text/format-text.c:1695 Initialised format: lvm2 global/format not found in config: defaulting to lvm2 config/config.c:764 global/format not found in config: defaulting to lvm2 Initialised segtype: striped striped/striped.c:220 Initialised segtype: striped Initialised segtype: zero zero/zero.c:100 Initialised segtype: zero Initialised segtype: error error/errseg.c:100 Initialised segtype: error Initialised segtype: snapshot snapshot/snapshot.c:165 Initialised segtype: snapshot Initialised segtype: mirror mirror/mirrored.c:261 Initialised segtype: mirror Setting backup/retain_days to 30 config/config.c:773 Setting backup/retain_days to 30 Setting backup/retain_min to 10 config/config.c:773 Setting backup/retain_min to 10 Setting backup/archive_dir to /etc/lvm/archive config/config.c:758 Setting backup/archive_dir to /etc/lvm/archive Setting backup/backup_dir to /etc/lvm/backup config/config.c:758 Setting backup/backup_dir to /etc/lvm/backup global/fallback_to_lvm1 not found in config: defaulting to 0 config/config.c:778 global/fallback_to_lvm1 not found in config: defaulting to 0 Parsing: lvremove /dev/main/rootbackup lvmcmdline.c:811 Parsing: lvremove /dev/main/rootbackup Processing: lvremove /dev/main/rootbackup lvmcmdline.c:835 Processing: lvremove /dev/main/rootbackup O_DIRECT will be used lvmcmdline.c:838 O_DIRECT will be used Setting global/locking_type to 1 config/config.c:773 Setting global/locking_type to 1 Setting global/locking_dir to /var/lock/lvm config/config.c:758 Setting global/locking_dir to /var/lock/lvm File-based locking enabled. locking/locking.c:137 File-based locking enabled. Using logical volume(s) on command line toollib.c:127 Using logical volume(s) on command line Locking /var/lock/lvm/V_main WB locking/file_locking.c:162 Locking /var/lock/lvm/V_main WB Opened /dev/hda1 RW device/dev-io.c:376 Opened /dev/hda1 RW /dev/hda1: block size is 512 bytes device/dev-io.c:134 /dev/hda1: block size is 512 bytes /dev/hda1: No label detected label/label.c:186 /dev/hda1: No label detected label/label.c:278 <backtrace> Opened /dev/hda2 RW device/dev-io.c:376 Opened /dev/hda2 RW /dev/hda2: block size is 512 bytes device/dev-io.c:134 /dev/hda2: block size is 512 bytes /dev/hda2: No label detected label/label.c:186 /dev/hda2: No label detected label/label.c:278 <backtrace> Opened /dev/hda3 RW device/dev-io.c:376 Opened /dev/hda3 RW /dev/hda3: block size is 4096 bytes device/dev-io.c:134 /dev/hda3: block size is 4096 bytes /dev/hda3: lvm2 label detected label/label.c:168 /dev/hda3: lvm2 label detected /dev/hda3: lvm2 label detected label/label.c:168 /dev/hda3: lvm2 label detected config/config.c:758 Setting cow_store to rootbackup config/config.c:758 Setting origin to root Read main metadata (6) from /dev/hda3 at 9216 size 1754 format_text/format-text.c:292 Read main metadata (6) from /dev/hda3 at 9216 size 1754 Setting activation/missing_stripe_filler to /dev/ioerror config/config.c:758 Setting activation/missing_stripe_filler to /dev/ioerror Getting device info for main-rootbackup activate/dev_manager.c:1015 Getting device info for main-rootbackup dm version O ioctl/libdm-iface.c:1315 dm version O dm info cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 O ioctl/libdm-iface.c:1315 dm info cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 O Do you really want to remove active logical volume "rootbackup"? [y/n]: y Archiving volume group "main" metadata. archiver.c:109 Archiving volume group "main" metadata. Locking LV cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 (NL) locking/file_locking.c:236 Locking LV cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 (NL) Finding volume group for uuid cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 metadata/metadata.c:804 Finding volume group for uuid cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 /dev/hda3: lvm2 label detected label/label.c:168 /dev/hda3: lvm2 label detected config/config.c:758 Setting cow_store to rootbackup config/config.c:758 Setting origin to root Read main metadata (6) from /dev/hda3 at 9216 size 1754 format_text/format-text.c:292 Read main metadata (6) from /dev/hda3 at 9216 size 1754 Found volume group "main" metadata/metadata.c:810 Found volume group "main" Getting device info for main-rootbackup activate/dev_manager.c:1015 Getting device info for main-rootbackup dm info cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 O ioctl/libdm-iface.c:1315 dm info cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 O Locking memory memlock_count inc to 1 dm names O Found existing layer 'main-root' Getting device info for main-root dm info main-root N Found existing layer 'main-rootbackup' Getting device info for main-rootbackup dm info main-rootbackup N Found existing layer 'main-rootbackup-cow' Getting device info for main-rootbackup-cow dm info main-rootbackup-cow N Found existing layer 'main-srv' Getting device info for main-srv dm info main-srv N Found existing layer 'main-home' Getting device info for main-home dm info main-home N Found existing layer 'main-root-real' Getting device info for main-root-real dm info main-root-real N Found active lv root Found active lv home Found active lv srv Found active lv rootbackup Getting target version for snapshot dm versions O Getting target version for snapshot-origin dm versions O Suspending main-root dm suspend main-root N Suspending main-rootbackup dm suspend main-rootbackup N Suspending main-root-real dm suspend main-root-real N Loading main-root-real Adding target: 0 10485760 linear /dev/hda3 384 dm reload cr4BQGigjdDUhseCmkOw1oLdVh63fT85x6pkSmEeXoa5MqB4QhJC9KkxEyyhtHua-real N Activated main-root-real cr4BQGigjdDUhseCmkOw1oLdVh63fT85x6pkSmEeXoa5MqB4QhJC9KkxEyyhtHua-real 253:001 Suspending main-rootbackup-cow dm suspend main-rootbackup-cow N Loading main-rootbackup-cow Adding target: 0 4194304 linear /dev/hda3 41943424 dm reload cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6-cow N Activated main-rootbackup-cow cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6-cow 253:000 Loading main-rootbackup Adding target: 0 10485760 snapshot 253:001 253:000 P 16 dm reload cr4BQGigjdDUhseCmkOw1oLdVh63fT85Zg7bQoiQT3w2SqvoLNYj2H6OwoCmjii6 N [hangs here]