Hello list, one our customer reported a issue. After executing lvextend, the vg underlying pv devs changed. I do a summary from my watching. first, pv devies in /etc/lvm/backup/systemvg & /etc/lvm/archive/systemvg-xxx are correct. but using pvdissect (url: https://wiki.syslinux.org/wiki/index.php?title=Development/LVM_support/pvdissect), the script dumped show pv related device had been changed after executing lvextend command. the part output of pvdissect like: ``` 0x00006000 (metadata.value): systemvg { id = "id-xxx" seqno = 11 format = "lvm2" status = ["RESIZEABLE", "READ", "WRITE"] flags = [] extent_size = 8192 max_lv = 0 max_pv = 0 metadata_copies = 0 physical_volumes { pv0 { id = "pv0-uuid-xxxx" <=== it didn't change device = "/dev/sdb" <=== it changed to /dev/sda status = ["ALLOCATABLE"] flags = [] dev_size = 4806528 pe_start = 2048 pe_count = 586 } pv1 { id = "pv1-uuid-xxxx" <=== it didn't change device = "/dev/sdc" <=== it changed to /dev/sdb status = ["ALLOCATABLE"] flags = [] dev_size = 4806528 pe_start = 2048 pe_count = 586 } pv2 { id = "pv2-uuid-xxxx" <=== it didn't change device = "/dev/sdd" <=== it changed to /dev/sdc status = ["ALLOCATABLE"] flags = [] dev_size = 4806528 pe_start = 2048 pe_count = 586 } ... ... # other parts are correct ``` (the systemvg consists of many LVs, ie: usrlv, varlv, optlv, homelv.)
my question: the devs order changed, but after system reboot, everything work fine. why? I not very familiar with lvm code. From my watching, it looks lvm uses pv uuid not device to work, is it right? Thanks. _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
