From: Sheldon Lee Wen (sheldon.leewen@cgi.com)
Date: Thu Nov 14 2002 - 11:44:19 EST
Many thanks for the quick responses.
Here is my original question:
Hi,
Does anyone know, or know where I can find out how tru cluster handles
PID's? Does it allow two instances of the same process on different
machines to have the same pid?
Thx.
Sheldon.
---------------------------
Here are the responses.
----------------------------
No it will not allow that. I cut and pasted a section from the Cluster
Application Migration section from one of the online guides -
Section 4.6 Expanded PIDs
In TruCluster Server, process identifiers (PIDs) are expanded to a full
32-bit value. The data type PID_MAX is increased to 2147483647
(0x7fffffff); therefore, any applications that test for PID <= PID_MAX
must be recompiled.
To ensure that PIDs are unique across a cluster, PIDs for each cluster
member are based on the member ID and are allocated from a range of
numbers unique to that member. The formula for available PIDs in a
cluster is:
PID = (memberid * (2**19)) + 2
Typically, the first two values are reserved for the kernel idle process
and /sbin/init. For example, PIDs 524,288 and 524,289 are assigned to
kernel idle and init, respectively.
Use PIDs to uniquely identify log and temporary files. If an application
does store a PID in a file, make sure that that file is member-specific.
Hope this helps...
Alay.
--------------------------
Sheldon,
http://www.tru64unix.compaq.com/docs/base_doc/DOCUMENTATION/V51A_HTML/AR
HH0DTE/CHPSSSXX.HTM
No, you would not be able to have two instances of the same
processes on different machines to have the same PIDs as the PIDs on
*each* node running 5.1A (cluster) have unique PID values.
Dan Price
-----------------------------
I've seen documentation on this - maybe in the Cluster Management book?
I just looked on my two-node cluster and the PIDs on one node are 524xxx
and on the other are 1048xxx. I seem to remember reading that the first
part is calculated such that they should never overlap in numbers.
Jenny Butler.
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