Hi list, I'm having one of those 'I'm stupid' -problems with LVM on CentOS 5.2. I've been working with traditional partitions until now, but I've finally been sold on the theoretical benefits of using LVM, but for now I only have a huge pile of broken filesystems to show for my efforts. My scenario; I attach a disk, either over USB or iSCSI. I create a PV on this device, create a VG using the device, and slice off a tiny LV for tests. [root at kasse ~]# dmesg usb 1-3: new high speed USB device using ehci_hcd and address 7 usb 1-3: configuration #1 chosen from 1 choice scsi27 : SCSI emulation for USB Mass Storage devices usb-storage: device found at 7 usb-storage: waiting for device to settle before scanning Vendor: ST375064 Model: 0A Rev: 3.AA Type: Direct-Access ANSI SCSI revision: 00 SCSI device sdg: 1465149168 512-byte hdwr sectors (750156 MB) sdg: Write Protect is off sdg: Mode Sense: 10 00 00 00 sdg: assuming drive cache: write through SCSI device sdg: 1465149168 512-byte hdwr sectors (750156 MB) sdg: Write Protect is off sdg: Mode Sense: 10 00 00 00 sdg: assuming drive cache: write through sdg: sdg1 sd 27:0:0:0: Attached scsi disk sdg sd 27:0:0:0: Attached scsi generic sg6 type 0 usb-storage: device scan complete [root at kasse ~]# pvcreate /dev/sdg1 Physical volume "/dev/sdg1" successfully created [root at kasse ~]# vgcreate testgroup /dev/sdg1 Volume group "testgroup" successfully created [root at kasse ~]# lvcreate -L 200M testgroup -n testLV Logical volume "testLV" created At this point, I have /dev/testgroup/testLV, which I can stick a fs on, mount, store files on, unmount, remount and recover the files from. Just as I'd expect. [root at kasse ~]# lvdisplay --- Logical volume --- LV Name /dev/testgroup/testLV VG Name testgroup LV UUID 3KjDiZ-gTAD-sC9E-sOSA-772o-41Yk-ZKK7cx LV Write Access read/write LV Status available # open 0 LV Size 200.00 MB Current LE 50 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:1 I have not explicitly set the vg active, as I understand that it implicitly will be set active in non-clustered environments like mine. LVM works as I'd expect it to up until here in any case. So - with the LV unmounted, I power my USB-device down, and then back up; [root at kasse ~]# dmesg usb 1-3: USB disconnect, address 7 usb 1-3: new high speed USB device using ehci_hcd and address 8 usb 1-3: configuration #1 chosen from 1 choice scsi28 : SCSI emulation for USB Mass Storage devices usb-storage: device found at 8 usb-storage: waiting for device to settle before scanning Vendor: ST375064 Model: 0A Rev: 3.AA Type: Direct-Access ANSI SCSI revision: 00 SCSI device sdi: 1465149168 512-byte hdwr sectors (750156 MB) sdi: Write Protect is off sdi: Mode Sense: 10 00 00 00 sdi: assuming drive cache: write through SCSI device sdi: 1465149168 512-byte hdwr sectors (750156 MB) sdi: Write Protect is off sdi: Mode Sense: 10 00 00 00 sdi: assuming drive cache: write through sdi: sdi1 sd 28:0:0:0: Attached scsi disk sdi sd 28:0:0:0: Attached scsi generic sg6 type 0 usb-storage: device scan complete (note that my disk is now sdi, not sdg, and connected on scsi28 and not scsi27) If I now try to access the device, all falls appart; [root at kasse ~]# lvdisplay /dev/testgroup/testLV: read failed after 0 of 4096 at 209649664: Input/output error /dev/testgroup/testLV: read failed after 0 of 4096 at 209707008: Input/output error /dev/testgroup/testLV: read failed after 0 of 4096 at 0: Input/output error /dev/testgroup/testLV: read failed after 0 of 4096 at 4096: Input/output error /dev/testgroup/testLV: read failed after 0 of 4096 at 0: Input/output error --- Logical volume --- LV Name /dev/testgroup/testLV VG Name testgroup LV UUID 3KjDiZ-gTAD-sC9E-sOSA-772o-41Yk-ZKK7cx LV Write Access read/write LV Status available # open 0 LV Size 200.00 MB Current LE 50 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:1 Trying to mount or otherwise access the LV also shows the problems; scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device printk: 25 messages suppressed. Buffer I/O error on device dm-1, logical block 30 Buffer I/O error on device dm-1, logical block 31 scsi 27:0:0:0: rejecting I/O to dead device Buffer I/O error on device dm-1, logical block 0 Buffer I/O error on device dm-1, logical block 1 Buffer I/O error on device dm-1, logical block 2 Buffer I/O error on device dm-1, logical block 3 Buffer I/O error on device dm-1, logical block 4 Buffer I/O error on device dm-1, logical block 5 Buffer I/O error on device dm-1, logical block 6 Buffer I/O error on device dm-1, logical block 7 scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device scsi 27:0:0:0: rejecting I/O to dead device hfs: unable to find HFS+ superblock So - LVM seems to believe my LV is still attached to scsi27, while it now actually sits on scsi28. What am I missing here? How do I get LVM to use a persistent device instead of a transient path? Yours, -S -- Simen Thoresen, Dolphin ICS Systems Administration and Wulfkit Support