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IBM/HACMP

How to synchronize timestamp

Re:How to synchronize VG timestamps??2 Years, 2 Months ago
Lets make things a little bit more easier:

- HACMP 5.4.1 => No timestamp file => timestamp is compared to the value in the ODM
- No enhanced Concuurent Mode VG => Terms active/passive do not apply

To determine the real state, execute the following command on both nodes:

lsattr -El <vgname> 

The output contains a value named timestamp => this is the value which HACMP will compare to the actual value on the VG.

Now, on the node where the VG is currently varied on, execute the following command an any disk contained in this VG, e.g. hdisk4:

lqueryvg -p hdisk4 -T

This command will read the timestamp directly from the disk. The value should be the same as given by the lsattr command.
If HACMP warns you about a timestamp Problem. the lsattr Command will show a different value on at least one of the nodes. To correct this problem, you need to use a command which reads the timestamp from the disk and writes it to the ODM => this is what synclvodm odm does. importvg -L should work as well as it will call synclvodm (this would be the better choice anyway as importvg is high level command).

In order to be able to call importvg -L, the disks of the VG need to be accessible. In non-concurremt environments, access is usually blocked through SCSI3 disk reservation.

Assuming node 1 has currently the VG online, and node 2 needs to execute importvg -L doe the follwoing:

on node 1: varyonvg -b -u -n <vgname> # this will break the reservation

on node 2: importvg -L <vgname> # this should update the time stamp in your ODM
on node 2: lsattr -El <vgname> # verify if the value has really changed

one node 1: restore the reservation with the following command: varyonvg -n <vgname>

What C-SPOC calls are some pretty complicated functions - not so easy to track if you are not really familiar to it. The easiest way to check what C-SPOC finally did, is to look in the logfile /tmp/cspoc.log or /var/hacmp/log/cspoc.log on the initiating node.

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