show processes memory
Displays memory usage statistics for all processes running on the Cisco Nexus switch.
Overview
The 'show processes memory' command is a vital diagnostic tool on Cisco Nexus switches running NX-OS. It provides a detailed snapshot of memory consumption by each running process, enabling network engineers to identify memory leaks, resource contention, and processes that may be approaching their allocated limits. Memory management is critical in network devices because insufficient memory can lead to process crashes, routing protocol failures, and overall system instability. On NX-OS, each process has a configurable memory limit (MemLimit) to prevent a single process from exhausting system resources. This command is typically used during performance troubleshooting, capacity planning, or when investigating unexplained behavior such as route flapping or slow convergence. It fits into a broader troubleshooting workflow: start with 'show system resources' for overall CPU/memory, then drill down with 'show processes memory' to pinpoint offending processes, and finally use 'show processes memory <process>' to focus on a specific process. Platform-specific behavior on Nexus includes the ability to sort output by various memory metrics and filter by process name. The command is non-disruptive and can be run at any time.
show processes memory [process-name | detail | sort [pid | name | size | limit | base | stack | heap | data | total]]When to Use This Command
- Identifying which process is consuming excessive memory, leading to performance degradation.
- Monitoring memory usage trends during normal operation and under load.
- Troubleshooting memory leaks by observing process memory growth over time.
- Verifying that critical processes have adequate memory allocation after configuration changes.
Parameters
| Parameter | Syntax | Description |
|---|---|---|
| process-name | show processes memory [process-name] | Optional process name to filter output for a specific process. If omitted, all processes are shown. |
| detail | show processes memory detail | Provides more detailed memory information, including per-process memory regions (text, data, stack, heap). |
| sort | show processes memory sort [pid | name | size | limit | base | stack | heap | data | total] | Sorts the output by the specified field. 'total' sorts by total memory used (MemUsed). Useful for identifying top consumers. |
Command Examples
Basic memory usage for all processes
show processes memoryPID ProcessName MemAlloc MemLimit MemUsed StackUsed HeapUsed DataUsed ----- -------------------- ---------- ---------- ---------- ---------- ---------- ---------- 1 init 1M 10M 512K 16K 256K 240K 2 kernel 5M 20M 3M 128K 1M 1.5M 100 bgp 50M 200M 45M 1M 30M 14M 200 ospf 30M 100M 28M 512K 18M 9.5M 300 lacp 10M 50M 8M 256K 5M 2.7M 400 stp 8M 40M 6M 128K 4M 1.9M 500 sysmgr 20M 100M 15M 1M 10M 4M 600 eth_port_channel 12M 60M 10M 512K 7M 2.5M 700 vpc 15M 80M 12M 768K 8M 3.2M 800 aclmgr 5M 30M 4M 256K 2.5M 1.2M 900 netstack 25M 150M 20M 2M 12M 6M
Each row shows a process with its PID, name, allocated memory (MemAlloc), memory limit (MemLimit), total memory used (MemUsed), and breakdowns: StackUsed, HeapUsed, DataUsed. High MemUsed relative to MemLimit indicates potential memory pressure.
Memory usage for a specific process (bgp)
show processes memory bgpPID ProcessName MemAlloc MemLimit MemUsed StackUsed HeapUsed DataUsed ----- -------------------- ---------- ---------- ---------- ---------- ---------- ---------- 100 bgp 50M 200M 45M 1M 30M 14M
Filters output to show only the BGP process. Useful for focused troubleshooting.
Memory usage sorted by total memory used
show processes memory sort totalPID ProcessName MemAlloc MemLimit MemUsed StackUsed HeapUsed DataUsed ----- -------------------- ---------- ---------- ---------- ---------- ---------- ---------- 100 bgp 50M 200M 45M 1M 30M 14M 200 ospf 30M 100M 28M 512K 18M 9.5M 900 netstack 25M 150M 20M 2M 12M 6M 500 sysmgr 20M 100M 15M 1M 10M 4M 700 vpc 15M 80M 12M 768K 8M 3.2M 600 eth_port_channel 12M 60M 10M 512K 7M 2.5M 300 lacp 10M 50M 8M 256K 5M 2.7M 400 stp 8M 40M 6M 128K 4M 1.9M 800 aclmgr 5M 30M 4M 256K 2.5M 1.2M 2 kernel 5M 20M 3M 128K 1M 1.5M 1 init 1M 10M 512K 16K 256K 240K
Sorts processes by total memory used (MemUsed) in descending order, highlighting the top consumers.
Understanding the Output
The 'show processes memory' output displays memory statistics for each process running on the Nexus switch. The key fields are: PID (process ID), ProcessName (name of the process), MemAlloc (memory allocated to the process), MemLimit (maximum memory allowed for the process), MemUsed (total memory currently used), StackUsed (stack memory used), HeapUsed (heap memory used), and DataUsed (data segment memory used). Healthy values show MemUsed significantly below MemLimit, with no process exceeding 80% of its limit. Problem values include MemUsed approaching or exceeding MemLimit, which can cause process crashes or system instability. Also, abnormal growth in HeapUsed or StackUsed may indicate memory leaks. The 'sort' option helps identify top memory consumers quickly.
Configuration Scenarios
Monitoring BGP memory usage after adding many routes
A Nexus switch is receiving a full BGP table from multiple peers, and memory usage is a concern.
Topology
Nexus-1 --- eBGP --- ISP-1
Nexus-1 --- eBGP --- ISP-2Steps
- 1.Check overall memory with 'show system resources'.
- 2.Use 'show processes memory bgp' to see BGP process memory.
- 3.Monitor MemUsed vs MemLimit; if approaching limit, consider increasing limit or reducing routes.
! Increase BGP memory limit (if supported) process memory limit bgp 300M
Verify: Run 'show processes memory bgp' again to confirm new limit and usage.
Watch out: Not all Nexus platforms allow changing process memory limits; check documentation.
Identifying a memory leak in OSPF process
OSPF process memory usage grows over time, eventually causing OSPF to restart.
Topology
Nexus-1 --- OSPF --- Router-2
Nexus-1 --- OSPF --- Router-3Steps
- 1.Run 'show processes memory ospf' periodically and log output.
- 2.Compare MemUsed over time; if increasing without bound, suspect memory leak.
- 3.Open a TAC case with the collected data.
! No configuration fix; requires software upgrade or patch.
Verify: After upgrade, monitor OSPF memory usage to confirm stability.
Watch out: Memory leaks may be intermittent; collect data over several days.
Troubleshooting with This Command
When troubleshooting memory issues on Cisco Nexus switches, start by checking overall system health with 'show system resources'. If memory utilization is high, use 'show processes memory sort total' to list processes by memory consumption. Look for processes with MemUsed close to or exceeding MemLimit. Common culprits include routing protocols (BGP, OSPF), especially with large tables, or processes like 'netstack' under heavy traffic. If a specific process is suspected, filter with 'show processes memory <process>'. For persistent issues, collect output at regular intervals to detect growth trends. On NX-OS, the system manager (sysmgr) monitors process memory and may restart processes that exceed their limits; check syslog for messages like 'Process <name> memory usage exceeded limit'. If a process repeatedly crashes, consider increasing its memory limit (if configurable) or reducing the load (e.g., fewer routes, less traffic). For memory leaks, a software upgrade may be necessary. Always compare with baseline values from when the switch was healthy.
CCNA Exam Tips
Know that 'show processes memory' is used to diagnose memory issues; high MemUsed relative to MemLimit is a red flag.
Remember the sort options: pid, name, size, limit, base, stack, heap, data, total – useful for targeted analysis.
On Nexus, memory limits are per-process; a process hitting its limit may be restarted by the system manager.
Common Mistakes
Confusing MemAlloc with MemUsed; MemAlloc is the reserved amount, not necessarily what's in use.
Ignoring the MemLimit column; a process using 90% of its limit is more concerning than one using 50% of a larger limit.
Assuming all memory is physical RAM; some memory may be virtual or shared.
Platform Notes
On Cisco Nexus switches running NX-OS, the 'show processes memory' command provides per-process memory statistics similar to Cisco IOS, but with some differences. NX-OS uses a different memory allocation model; processes have explicit memory limits (MemLimit) that are not present in IOS. In IOS, 'show processes memory' shows memory used but not per-process limits. The NX-OS command also supports sorting and filtering options not available in IOS. Equivalent commands on other platforms: on Juniper Junos, use 'show system processes extensive' or 'show task memory'; on Arista EOS, use 'show processes memory'. On NX-OS, the 'detail' option provides additional memory region breakdowns. Version differences: earlier NX-OS versions may not support the 'sort' parameter; always check the command reference for your specific version. The command is available in all NX-OS modes (EXEC).
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