Archive for April 2010

Missing device file

In our ESX environment, I extended a virtual disk from VirtualCenter and created a new partition on it using fdisk. The new partition was to be added to a Volume Group under LVM. But the OS (RHEL5 in this case) didn’t recognize the partition. “pvcreate” said it could not find the the device it was “Ignored by filtering” – As it turned out it was not so much a question of filtering as the fact that the device file was missing; /dev/sdb2 simply did not exist. I did a lot of searching and jumping through hoops for a solution that did not include a reboot (the server in question is a production server) – While there might very well be other solutions to this – the one I found turned out to be quite simple: Don’t use fdisk – use “parted” instead:

parted DEVICE
(parted) mkpart PART-TYPE START END
(parted) toggle PART-NUMBER FLAG

in my case it looked like this:

parted /dev/sdb
(parted) mkpart primary 53.7GB 107GB
(parted) toggle 2 lvm
(parted) print
Model: VMware Virtual disk (scsi)
Disk /dev/sdb: 107GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number  Start   End     Size    Type     File system  Flags
 1      32.3kB  53.7GB  53.7GB  primary               lvm
 2      53.7GB  107GB   53.7GB  primary               lvm

And Voila! – you’ll have a new partition AND the corresponding device file!