How do filesystem snapshots work in AIX?

To perform valid backups of your database, it is important to suspend the database. This prevents modifications of files during the backup process. By taking a point-in-time snapshot of your database files, your backup program will be capturing a “frozen” database instead of an “in motion” database.

Eclipse has an updated backup script that uses database suspension with snapshots to create point-in-time images of your database files. If you would like this script installed on your AIX server, please submit a service request for the support team to review your system’s configuration, validate that it meets the appropriate requirements, and implement the changes.

The snapshot script is typically scheduled to run at regular intervals via crontab to create new filesystem snapshots.

After running the script, the snapshot filesystems are mounted under /snap, allowing read-only access by backup software. For example, the snapshot of the /u2/eclipse/LEDGER file would be located at /snap/u2/eclipse/LEDGER. When configuring backup software, it is recommended to backup every file under /snap/u2.

Since every change (delta) between the snapshot and the “live” filesystem must be recorded, the snapshots have a finite lifespan. By default, the snapshot script is configured to hold 1GB of changes before requiring a refresh. On busier systems, or on systems where the snapshots must be retained for a longer period of time to accommodate a slow backup process, the snapshot volume size may be increased by editing the snapshot backup script.

When the snapshot volume has reached its maximum capacity for tracking changes, it must be recreated by running the snapshot script again.

For troubleshooting purposes, a log of the snapshot backup script is kept at /tmp/snapsave.log.

For more information, refer to the following resources:

Configuring Fax on Demand

The VSI-FAX server installation program automatically installs the Fax on Demand Connector and creates a fax destination called FoDC for you. This is the destination that should be used for sending fax jobs to the Esker Fax on Demand server.

To be able to fax through Esker on Demand, you simply need to enter the following connection information you should have received via email when subscribing to the service:

  • Account ID
  • Password

To configure the connector:

vfxadmin config -a -i FODC DEVICE hostname
vfxadmin config -a -i FODC DEVICE accountid 00012345
vfxadmin config -a -e -i FODC DEVICE password WwVEbyrp

To enable the connector:

vfxadmin enable fodc

If you are migrating from a VSI-FAX configuration that used modems, you’ll need to remove the existing default fax1 class and replace it with a new one containing only fodc:

vfxadmin class -d -a fodc temp
vfxadmin class -x fax1
vfxadmin class -d -a fodc fax1
vfxadmin class -x temp

If you are not using modems, and this is your first time configuring VSI-FAX, all you need to do is create a “class” called “fax1” and add the device “fodc” to the fax1 class:

vfxadmin class -d -a fodc fax1

When the connector has been configured and set as the default destination, you are ready to fax via Fax on Demand.

Esker’s service requires 10-digit dialing, so you should verify that Eclipse is configured to use 10-digit dialing rather than 7-digit dialing: F2 -> P -> A -> Fax -> ALT-F

Testing the Fax on Demand Connector

To send a test fax via FoDC:

vfx -n +5087788384 -d FoDC /etc/hosts

To check the status (where 1013 is the fax job number output from the previous command):

vfxstat 1013


How do I check my fax failure rate?

First, run the following command to list the result of each fax attempt:

vfxolog -d | egrep -v "^Req|QUEUED|SNDING" | awk '{print $9}' | sort | uniq -c | sort -rn

Here’s output from an example system experiencing issues with fax reliability:

root@eclipse ~]# vfxolog -d | egrep -v "^Req|QUEUED|SNDING" | awk '{print $9}' | sort | uniq -c | sort -rn
    489 NORMAL
    100 LINDRP
     86 TMEOUT
     83 BUSY
     31 NOTFAX
      4 CANCEL

Each stats code means something different, but for the purposes of this investigation we care mostly about the good status (NORMAL) vs. the bad status (LINDRP and TMEOUT).

To calculate the fax failure percentage: (LINDRP + TMEOUT) / (LINDRP + TMEOUT + NORMAL).

How do I increase the size of my AIX dump device?

If you are receiving the following error in your AIX errpt, you need to increase the size of your dump device:

E87EF1BE   0925150011 P O dumpcheck      The largest dump device is too small.

First, identify the largest dump device using the “/usr/lib/ras/dumpcheck -p” command, as in the following example:

eclipse:root:/# /usr/lib/ras/dumpcheck -p
The largest dump device is too small.

Largest dump device
Largest dump device size in kb
Current estimated dump size in kb

In this example, the “dump device” that needs to be increased is “lg_dumplv”. If a file system needs to be increased, the output will give a “file system name”.

If a logical volume needs to be increased, review the current size of this logical volume using the lslv command, similar to the following example:

eclipse:root:/# lslv lg_dumplv
LOGICAL VOLUME:     lg_dumplv              VOLUME GROUP:   rootvg
LV IDENTIFIER:      0001c02b0000d60000000114a8a42e67.11 PERMISSION:     read/write
VG STATE:           active/complete        LV STATE:       opened/syncd
TYPE:               sysdump                WRITE VERIFY:   off
MAX LPs:            512                    PP SIZE:        128 megabyte(s)
COPIES:             1                      SCHED POLICY:   parallel
LPs:                8                      PPs:            8
STALE PPs:          0                      BB POLICY:      relocatable
INTER-POLICY:       minimum                RELOCATABLE:    yes
INTRA-POLICY:       middle                 UPPER BOUND:    32
MOUNT POINT:        N/A                    LABEL:          None
Serialize IO ?:     NO

Note the number of LPs, and increase the logical volume by a reasonable extent. In this example, I can double the size of the logical volume by adding an additional 8 LPs, as shown in the example command below:

eclipse:root:/# extendlv lg_dumplv 8

If a file system needs to be increased, review the current and estimated sizes of the file system provided by the dumpcheck utility. Then, expand the filesystem using a command similar to the following example:

chfs -a size=8G /var/adm/ras

Once you have confirmed the new size same lslv or df commands, run the same dumpcheck command to verify that no errors or warnings are generated. If the situation has been resolved, running the dumpcheck command will simply return you to the command prompt with no errors.

For more information on the AIX dump device, it’s purpose, and more detailed troubleshooting steps, see IBM’s website: Increase the Size of a Dump Device