How to Allocate Core Memory Buffers

Linux and Unix based storage systems may report error messages like ”Cannot allocate core memory buffers.” Although there is no way to manually allocate memory buffers, there are often program options or other adjustments that solve these issues. Memory allocation occurs deep within the program code and these errors are symptoms of deeper problems. Memory may be consumed by other programs or the storage system may need some adjustments. Try these tips to solve these memory problems.

Instructions

1. Search the web for the error message. Open a web browser, go to an Internet search engine and type the name of the program causing the error followed by the exact error message. In most cases, someone has experienced the same problem and has posted a solution.

2. Read the troubleshooting section of the program’s user manual. Remedies found in the manual may describe issues similar to your symptoms and these may guide you to a solution.

3. Determine current memory usage. From the command prompted, enter the command:

   $ free -k

   The –k options reports the memory usage in kilobytes. Output will look something like this:

   total used free shared buffers cached
   Mem: 7669084 7613552 55532 0 184680 1703796
   -/+ buffers/cache: 5725076 1944008
   Swap: 2096440 1694036 402404

   The first line shows total memory. Compare the first number, total memory, to the second number, amount used, and the third, the remaining free memory. If the total used is more than 85 or 90 percent, then there is a good chance that one or more processes are using too much memory. Also look at the third line labeled "Swap." This is the amount of swap space used, often because there is insufficient physical memory to handle the workload.

4. View the process list. When memory usage exceeds available resources, the choices are to remove unnecessary processes or to add more memory. From the command prompt, enter:

   $ps –aux

   This command lists each running process, the owner or user, elapsed CPU time and memory usage. Similar to the task manager list in Windows, this command will point toward the processes using the most memory and CPU.

   Many Linux distributions install quite a bit of software that is never used or necessary. If a process is taking quite a bit of memory, look it up on the Internet and see if it can be removed. If so, use "apt-get" or "rpm" to remove the program.

5. Add memory. If all other solutions fail to solve the problem, add more memory. First, determine the maximum memory allowed for the CPU and motherboard and, if possible, purchase and add the memory.

Tips & Warnings

• Before making any changes, remember to back up the hard disks.

References

• The Linux Information Project : How to use the "free" command
• The Linux Information Project: The ps Command
• Santosa, Mulyadi: When Linux Runs Out of Memory