SharePlex 10.2 - Administration Guide

If database corruption or other system problem forced you to shut down SharePlex, verify that SharePlex released the semaphores and shared memory that it was using.

To verify and release semaphores

1. Look for any SharePlex processes that did not shut down, and kill them.

   $ ps -ef | grep sp_

   $ kill -9 PID

2. Change directories to the rim sub-directory of the SharePlex variable-data directory, then issue the od -x command for the shmaddr.loc and the shstinfo.ipc files.

   # od -x shmaddr.loc

   0000000 0000 00e1 ed40 0000 4400 9328 0080 0000

   0000020 0002 0021

   0000024

   # od -x shstinfo.ipc

   0000000 0000 00e0 ee90 0000 4100 9328 0010 0000

   0000020 0002 0020

   0000024

3. Make a note of the following values:

   • The first 32-bit word of each of the files above reveals the hexadecimal equivalent of the ID of the shared memory segment. Convert this value to decimal. For example, in the shmaddr.loc file shown in step 2, the first word is 0000 00e1, which equates to a decimal value of 225. In the shstinfo.ipc file, the first word is 0000 00e0, which equates to a decimal value of 224.
   • The third word of the shmaddr.loc and the shstinfo.ipc files reveals the hexadecimal equivalent of the KEY of the shared memory segment and the semaphore. (Each set has the same key value.) Do not convert this value to decimal. For example, in the shmaddr.loc file, the third word is 4400 9328. In the shstinfo.ipc file, the third word is 4100 9328.
   • The fifth word of each file is the SEMAPHORE ID. Convert this value to decimal. The semaphore IDs in the examples are hex 0002 0021 and 0020 0020, which in decimal are 131105 and 131104, respectively.

4. Issue the ipcs -smaa command to view all of the shared memory segments and semaphores. (Shared memory segments are listed first and are denoted with an “m.” Semaphores are denoted with an “s.”) The display looks similar to the following, but will be more extensive.

   

5. Verify that the shared memory IDs from the shmaddr.loc and shstinfo.ipc are in the list and that the keys match.

6. For each shared memory segment, verify that the value in the NATTCH column is 0. This ensures that the SharePlex processes that you killed released their memory segments.

7. For the semaphores, verify that the semaphore IDs and keys match the file values.

8. As root, issue the ipcrm -m command for the ID values (224 and 225 in the examples) to remove the memory segments.

   # ipcrm -m 224

   # ipcrm -m 225

9. As root, issue the ipcrm -s command for the key values (131104 and 131105 in the examples) to remove the semaphores.

   # ipcrm -s 131104

   # ipcrm -s 131105