Platform: RHEL4 2.6.9-55.0.9.ELsmp x86_64. In part, this is a redirect (not cross-post) from https://www.redhat.com/archives/nahant-list/2007-October/msg00020.html I have a single-PV VG on a 2.7TB LUN on an Apple Xserve RAID, multipath fibre channel-attached. The 2.7TB LUN regularly "disappears," I think whenever multipath does anything (including regular multipathd checks). Currently a filesystem on that LUN is mounted RW and shows up in dmsetup, but not in lvscan. The relevant /etc/lvm/backup/ file has this fascinating tidbit: dev_size = 1565605888 # 746.539 Gigabytes pe_start = 384 pe_count = 715401 # 2.72904 Terabytes The physical extents are larger than the device? Looks like it wrapped at 2TB. Why did it let me do that? I knew that I couldn't create a > 2TB partition with fdisk, but I didn't understand that on a 64-bit OS, I couldn't point LVM2 at a > 2TB raw disk. (Is that in fact the problem?) More ugly history: The LUN had been used by a Windows machine, with a GUID partition table. I overwrote the first several blocks with zeroes and created a single-PV VG taking up the whole 2.7TB, then pointed pvcreate at the parent devive-mapper path for the disk (not the partitions). Unfortunately, I did not blow away the backup GPT, so those partitions popped up again upon reboot. Oops. But that history is probably beside the point. I would like to resolve this without recreating the filesystem, which has a large amount of data on it. The filesystem works just fine (doesn't it?), as long as I don't reboot. :-| The start of the filesystem is easy to find, and it is exactly 2TB long (I created the LV with padding), so there should be no problem: [root@mail2 ~]# dd if=/dev/sdd bs=512 count=1 skip=384 count=3 of=/tmp/fs 3+0 records in 3+0 records out [root@mail2 ~]# file /tmp/fs /tmp/fs: Linux rev 1.0 ext3 filesystem data (needs journal recovery) (large file s) So, [how] can I create a partition with parted that happens to land at the right blocks? Can I safely reduce the "pe_start" parameter of the LVM by the partition overhead, which appears to be 34 blocks, then pvcreate --restorefile the modified config? # Generated by LVM2: Thu Jul 19 23:23:35 2007 contents = "Text Format Volume Group" version = 1 description = "Created *after* executing 'lvcreate -L2T -n lvZimbraBackup1 vgZimOffsite'" creation_host = "mail2.its.carleton.edu" # Linux mail2.its.carleton.edu 2.6.9-55.0.2.ELsmp #1 SMP Tue Jun 12 17:58:20 EDT 2007 x86_64 creation_time = 1184905415 # Thu Jul 19 23:23:35 2007 vgZimOffsite { id = "vqX3RX-7JVH-UVCE-4Zfh-xa6F-hak8-gih0v8" seqno = 2 status = ["RESIZEABLE", "READ", "WRITE"] extent_size = 8192 # 4 Megabytes max_lv = 0 max_pv = 0 physical_volumes { pv0 { id = "9yEHDP-hVi2-W72J-wWAP-loRk-6Do5-5SQwe0" device = "/dev/dm-4" # Hint only status = ["ALLOCATABLE"] dev_size = 1565605888 # 746.539 Gigabytes pe_start = 384 pe_count = 715401 # 2.72904 Terabytes } } logical_volumes { lvZimbraBackup1 { id = "GCeeRm-oKFZ-Rqz9-vM0w-zegj-PljH-bAv9qm" status = ["READ", "WRITE", "VISIBLE"] segment_count = 1 segment1 { start_extent = 0 extent_count = 524288 # 2 Terabytes type = "striped" stripe_count = 1 # linear stripes = [ "pv0", 0 ] } } } } -- Rich Graves http://claimid.com/rcgraves Carleton.edu Sr UNIX and Security Admin CMC135: 507-646-7079 Cell: 952-292-6529 _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
