Greetings. An evil query for experts:
Last year I posted a question on how to get started with the Logical Volume Manager. Nobody responded and, looking back on it, I don't blame y'all. But now I have bitten the bullet, created 2 physical volumes (/dev/sda5, /dev/sda6), and two volume groups (vg-db01, db-vg02) and a total of 4 logical volumes of 1GB each. I'll be creating more as I go along but I have one problem:
The logical volumes I created with lvcreate are all Block devices.
Note - I used the -L option in the ls command because the device files named are actually symlinks to the block special device files. For example:
$ find /dev/vg-db01 /dev/vg-db02 |xargs ls -lL
brw-rw---- 1 root disk 252, 0 2011-01-30 15:50 /dev/vg-db01/lvol-db001
brw-rw---- 1 root disk 252, 1 2011-01-30 15:55 /dev/vg-db01/lvol-db002
brw-rw---- 1 root disk 252, 2 2011-01-30 15:55 /dev/vg-db01/lvol-db003
brw-rw---- 1 root disk 252, 3 2011-01-30 16:03 /dev/vg-db02/lvol-db001
I have mentioned in the past that I am an Informix DBA. When I worked the LVM on HP-UX and AIX, whenever I created a new logical volume, it created a block device file, as above as well as a character device file. In that case, the ls output would have looked like:
$ ls -l /dev/vg-db01/lvol-db001
lrwxrwxrwx 1 root root 7 2011-01-30 15:50 /dev/vg-db01/lvol-db001 -> ../dm-0
When I worked on a Red Had environment, I was not a system admin but the character raw volumes came up just the same.
crw-rw---- 1 root disk 252, 0 2011-01-30 15:50 /dev/vg-db01/rlvol-db001
I have not found any raw disk volumes post creation of the primary lvols. I have been using find to look for -type c files under /dev.
Perhaps I needed an option under vgcreate but I have not found that in the man pages.
Note: For the Informix-savvy out there: I know I don't really need to use raw volumes to bypass the cache (as Informix engines prefer); I know there is a mount option in /etc/fstab to sync all writes in a mounted file system. But I am doing this as a training exercise and I need to know it.
How do I create the character disk device files to correspond to the block device files already created and in the future? If I need to go back and recreate the volume groups I will do so.
Thanks much for help here.