IBM AIX Administrator cheat sheet

AIX 7.2 System Administration

• LVM hierarchy: physical volume (PV) -> volume group (VG) -> logical volume (LV) -> file system; a PV is divided into physical partitions (PPs), each typically 16 MB for AIX native VGs, and each LP maps to one or more PPs depending on the LV copy count.

• Mirroring rule: mklv -c 2 gives two copies; total PPs consumed = LPs x copy count, so a mirrored LV needs twice the free PPs. lslv -m lvname shows the LP-to-PP mapping across disks.

• Stale partitions occur when a disk is removed without reducevg; clear them with syncvg -p pvname or varyonvg diagnostics. lsvg -p vgname lists PV state (active/missing/stale).

• Rootvg mirroring: extendvg rootvg hdisk1, then mirrorvg rootvg, then bosboot -ad /dev/hdisk1 and bootlist -m normal hdisk0 hdisk1. Without bosboot the second disk is not bootable.

• File system types: JFS2 is default; crfs -v jfs2 -g vg -m /mnt -a size=1G creates it. chfs -a size=+512M /mnt grows online; JFS2 can be shrunk with chfs -a size=-... only if it is unmounted and not a snapshot target.

• df -g reports in GB blocks, df -i reports inodes. JFS2 dynamic inode allocation means inode exhaustion is rare; istat shows per-file inode detail and ncheck maps inodes back to paths.

• Boot sequence: POST -> bootlist device -> BLV (boot logical volume, hd5) -> /etc/inittab init phase. bootinfo -b shows the last boot device; bosboot -a rebuilds hd5 from /unix and /usr/lib/boot.

• Error logging: errpt -a shows detailed entries, errpt -d H hardware only, errclear 0 clears all. errdemon controls the log; errlogger writes a custom message into the log.

• lsvg -l vgname shows LV types (jfs2, paging, sysdump, boot, jfslog). The JFS2 log is a logical volume (usually hd8) and must be at least 4 MB; logform reformats it only when unmounted.