Simen Timian Thoresen wrote: > nate wrote: >> Simen Timian Thoresen wrote: >> >>> So - with the LV unmounted, I power my USB-device down, and then back >>> up; >> > > Hi Nate, > >> I believe your problem is you didn't deactivate the logical >> volume, and export the volume group before disconnecting. > > Yes! Thank you - exporting and then importing again after replugging > worked. > > I'll have to read up on what actually happens here .-) > > Still - say that the USB (or iSCSI) PV is not exported before being > unplugged (cables tripped over, internet connection going down, etc) - > how do I recover from an unplugged but not exported PV/VG? It seems that > vg[im/ex]port only fiddle with the off-PV metadata. Is this correct? > > I think I'm looking for a force-import that allows me to bring a VG with > associated LVs up provided that the PVs are present - affectively a > 'assemble' ala mdadm. Hah! I got this one on my own. After unplugging, I removed the /etc/lvm/archive/ /etc/lvm/backup and /dev/mapper/<device> entries, and then replugged; [root at kasse ~]# pvscan PV /dev/iscsi_01 VG iscsistorage lvm2 [102.79 GB / 102.59 GB free] Total: 1 [102.79 GB] / in use: 1 [102.79 GB] / in no VG: 0 [0 ] (this I've seen before) Thinking that I could import the VG, I found that it's impossible to imoport a non-exported VG; [root at kasse ~]# vgimport -a Volume group "iscsistorage" is not exported ...but just setting it active worked; [root at kasse ~]# vgchange -a y iscsistorage 1 logical volume(s) in volume group "iscsistorage" now active [root at kasse ~]# lvdisplay /dev/mapper/iscsistorage-lv1: open failed: No such file or directory /dev/mapper/iscsistorage-lv1: open failed: No such file or directory --- Logical volume --- LV Name /dev/iscsistorage/lv1 VG Name iscsistorage LV UUID mKP1DG-Pc1q-vFzf-sR9v-RE3e-ChNV-T0dWq1 (...) ...and the LV is not mountable; [root at kasse ~]# mount /dev/iscsistorage/lv1 /mnt/ mount: special device /dev/iscsistorage/lv1 does not exist To remove the missing /dev/mapper entries, I exported and then reimported the VG; [root at kasse ~]# vgexport -a Volume group "iscsistorage" successfully exported [root at kasse ~]# vgimport -a Volume group "iscsistorage" successfully imported [root at kasse ~]# lvdisplay --- Logical volume --- LV Name /dev/iscsistorage/lv1 VG Name iscsistorage LV UUID mKP1DG-Pc1q-vFzf-sR9v-RE3e-ChNV-T0dWq1 (...) [root at kasse ~]# mount /dev/iscsistorage/lv1 /mnt/ [root at kasse ~]# ls /mnt/ lost+found (...) Woila! I think I saw someone doing something to /dev/mapper/control as well to skip the export-reimport steps. I'll see if I can robustify this a little, but if this works, I'll be significantly closer to my main goal. Thank you again for your help .-) Yours, -S > Thank you for pointing me in the right way ;-) > > -S > >> lvchange -a n <path to lvm> >> vgexport -a (don't worry it will only export groups that are >> ready to be exported) >> >> Now you can safely power the device down(provided the VG was >> successfully exported, all logical volumes must be unmounted >> and deactivated before it will succeed). >> >> when you power it back up run >> >> pvscan >> vgimport -a >> lvchange -a y <path to lvm> >> >> LVM is very useful for volumes that change device names, but you >> must use it properly otherwise bad things will happen as you >> saw. >> >> If you want to have USB mount automatically it may be better >> to put a label on the file system, at least in Debian(don't >> have a CentOS system with a USB disk handy here) the volume >> is mounted as /media/<disk label> if there is a disk label. >> You can use the e2label command to label the device. I'd >> expect CentOS to likely behave similarly to debian in this >> respect. >> >> nate >> >> >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> http://lists.centos.org/mailman/listinfo/centos >> > > -- Simen Thoresen, Dolphin ICS Systems Administration and Wulfkit Support