Pool expansion failed

[Shruthi K Prakashan · Accepted solution]

Toine,

You can collect the information that Hoffman suggested on your running system itself. You don't need a dump.

$anal/system
SDA> CLUE MEMORY/STATISTICS
SDA> SHOW POOL/NONPAGED/SUMMARY ( What is the % of 'Total space utilization' here ? )
SDA> SHOW MEMORY/POOL/FULL

Additionally, also do a

SDA> CLUE MEMORY/LOOKASIDE

Do you see any lookaside list of a particular size being heavily populated ?

Also, there seems to be a large part of the pool free ( 899.25 MB in 960 MB ).

Dynamic Memory Usage: Total Free In Use Largest
Nonpaged Dynamic Memory (MB) 960.00 899.25 60.75 0.31

It may be useful to figure out what might have triggered pool expansion in the first place.

Can you also check,

SDA> SHOW POOL/NONPAGED/STATISTICS

How many packets do you see on the variable list ?

This could give you an idea on the amount of pool fragmentation.

You can enable POOLCHECK using :

$ mc sysgen
SYSGEN> USE ACTIVE
SYSGEN> SET POOLCHECK %X61640000
SYSGEN> WRITE ACTIVE
SYSGEN> exit

And then, examine the content of the ring buffer periodically to track the allocations and deallocations.

$ anal/sys
SDA> SHOW POOL/RING

- Shruthi

[SDIH1]

>I think Hoff is correct some application is >filling the pool.

>I use TCPIP 5.6 ECO 4 and have many active >BG devices.

We had similar problems were a TCP client on a remote machine kept wrting to the TCP socket on an IA64 OpenVMS system running TCPIP 5.6, but at the VMS side the connection was never read.

On TCPIP 5.4 this was never a problem, as there once the buffer of the TCPIP socket was filled up (to 512 bytes?), it stopped accepting data from the remote system.

In TCPIP 5.6 these buffers will be filled up until all NPAGEDYN is used.

We found the devices filling up by doing pipe ucx show device /full | search sys$input "alloc". Some devices showed this:

QLIMIT 0 Total buffer alloc 32143360 0

We found 2 solutions: read the device at the VMS side, stop writing at the client side.

[Toine_1]

Hi,

The problem was caused by then network interface. There were many packets on the lookaside list (LAL). All these packets were VCR packets. I think that one server has sent a lot of data to this Rx6600 server and couldn't be handled in time.

After rebooting the server the non paged pool became normal.
In OpenVMS 8.4 there will be an enhancement that there will be max 5000 LAN packets outstanding for a application to avoid pool expansion problems.

Thank you all for the help.

/Toine