You may run into an issue with opening a virtual terminal window on an OLD HMC version (version 3.3.6). You can access the HMC through ssh, but opening a terminal window doesn't work. This ocurs when the HMC is in use for a full system partition on a frame:

At the fist attempt to login through ssh to the HMC and running vtmenu:

# ssh -l hscroot hmc
hscroot@hmc's password:
hscroot@lawhmc2:~> vtmenu

 Retrieving name of managed system(s) . . . 

 ----------------------------------------------------------
  Managed Systems:
 ----------------------------------------------------------
   1) 10XXXXX-XXXX
   2) 10YYYYY-YYYY
   3) 10ZZZZZ-ZZZZ

 Enter Number of Managed System.   (q to quit): 3

 ----------------------------------------------------------
  Partitions On Managed System:  10ZZZZZ-ZZZZ
 ----------------------------------------------------------

 Enter Number of Running Partition (q to quit):

A very nice command to use when you either want to show someone remotely how to do something on AIX, or to allow a non-root user to have root access, is portmir.

First of all, you need 2 users logged into the system, you and someone else. Ask the other person to run the tty command in his/her telnet session and to tell you the result. For example:

user$ tty
/dev/pts/1

root# portmir -t /dev/pts/1

# portmir -o

JFS2 filesystems allow you to create file system snapshots. Creating a snapshot is actually creating a new file system, with a copy of the metadata of the original file system (the snapped FS). The snapshot (like a photograph) remains unchanged, so it's possible to backup the snapshot, while the original data can be used (and changed!) by applications. When data on the original file system changes, while a snapshot exists, the original data is copied to the snapshot to keep the snapshot in a consistant state. For these changes, you'll need temporary space, thus you need to create a snapshot of a specific size to allow updates while the snapshot exists. Usually 10% is enough. Database file systems are usually not a very good subject for creating snapshots, because all database files change constantly when the database is active, causing a lot of copying of data from the original to the snapshot file system.

In order to have a snapshot you have to:

• Create and mount a JFS2 file system (source FS). You can find it in SMIT as "enhanced" file system.
• Create a snapshot of a size big enough to hold the changes of the source FS by issuing smitty crsnap. Once you have created this snapshot as a logical device or logical volume, there's a read-only copy of the data in source FS. You have to mount this device in order to work with this data.
• Mount your snapshot device by issuing smitty mntsnap. You have to provide a directory name over which AIX will mount the snapshot. Once mounted, this device will be read-only.

# snapshot -o snapfrom=$FILESYSTEM -o size=${SNAPSIZE}M

# snapshot -q $FILESYSTEM

# mkdir -p /snapshot$FILESYSTEM

# SNAPDEVICE=`snapshot -q $FILESYSTEM | grep -v ^Snapshots | grep -v ^Current | awk '{print $2}'`

# mount -v jfs2 -o snapshot $SNAPDEVICE /snapshot$FILESYSTEM

# unmount /snapshot$FILESYSTEM

# snapshot -d $SNAPDEVICE

# rm -rf /snapshot$FILESYSTEM

To mount:

1. Build a logical volume (the size of an ISO image, better if a little bigger).
2. Create an entry in /etc/filesystem using that logical volume (LV), but setting its Virtual File System (V'S) to be cdrfs.
3. Create the mount point for this LV/ISO.
4. Copy the ISO image to the LV using dd.
5. Mount and work on it like a mounted CD-ROM.

/IsoCD:

dev = /dev/lv09
vfs = cdrfs
mount = false
options = ro
account = false

1. Unmount the file system.
2. Destroy the logical volume.

To add a PVID to a disk, enter:

# chdev -l vpathxx -a pv=yes

# chpv -C vpathxx

To monitor all lpars within 1 frame, use:

# topas -C

There are times that you would like to create some "load" on the system. A very, very easy way of keeping a processor very busy is:

# yes > /dev/null

If you wish to clone a system with a mksysb, then you can do so, but you do not want your cloned system to come up with the same TCP/IP information. Just issue rmtcpip before creating the mksysb, and you have a perfect image for cloning to another system. Be sure to issue this command at a terminal, as you will lose your network connection!

If you get this error, you probably have one of the following things wrong:

• You've forgotten the slash and semicolon in the find command. Use find command like this:

  # find /tmp -mtime +5 -type f -exec rm {} \;

• If you get this error from crontab, then you should add an extra slash to the slash and semicolon. Use the find command like this:

  0 2 * * * find /tmp -mtime +5 -type f -exec rm {} \\;

An AIX system should have a single default gateway defined. However, sometimes, it does occur that a system has multiple default gateways. Here's information to detect multiple default gateways and how to get rid of them:

First, obtain how many gateways there are:

# odmget -q "attribute=route" CuAt

CuAt:
        name = "inet0"
        attribute = "route"
        value = "net,-hopcount,0,,0,192.168.0.1"
        type = "R"
        generic = "DU"
        rep = "s"
        nls_index = 0

CuAt:
        name = "inet0"
        attribute = "route"
        value = "net,-hopcount,0,,0,192.168.0.2"
        type = "R"
        generic = "DU"
        rep = "s"
        nls_index = 0

# chdev -l inet0 -a delroute="net,-hopcount,0,,0,192.168.0.2"
Method error (/usr/lib/methods/chginet):
        0514-068 Cause not known.
0821-279 writing to routing socket: The process does not exist.
route: not in table or multiple matches
0821-207 chginet: Cannot add route record to CuAt.

# odmget -q "attribute=route" CuAt

CuAt:
        name = "inet0"
        attribute = "route"
        value = "net,-hopcount,0,,0,192.168.0.1"
        type = "R"
        generic = "DU"
        rep = "s"
        nls_index = 0