Context
Aerospike uses System V shared memory segments for several internal data structures, depending on namespace and storage configuration.
In some cases, it is useful to identify which shared memory segments belong to Aerospike and to estimate how much memory has been allocated.
Method
You can use the ipcs command to inspect shared memory segments.
List shared memory segments:
sudo ipcs -m
example output:
root@asd70-1:/# ipcs -m ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0xae001100 14 root 666 1073741824 1 0xad001000 15 root 666 402653184 1 0xad001001 16 root 666 402653184 1 0xad001002 17 root 666 402653184 1 0xad001003 18 root 666 402653184 1 0xad001004 19 root 666 402653184 1 0xad001005 20 root 666 402653184 1 0xad001006 21 root 666 402653184 1 0xad001007 22 root 666 402653184 1
Common Aerospike shared memory key prefixes include:
- 0xae : primary index (PI)
- 0xa2 : secondary index (SI)
- 0xad : in-memory data segments
The following command can be used to filter for Aerospike Shared memory segments:
ipcs -m | sed "s/ .*$//" | egrep 0xa[de2]
To double check the creator and last-operation PIDs of the shared memory segments:
root@asd70-1:/# ipcs -mp ------ Shared Memory Creator/Last-op PIDs -------- shmid owner cpid lpid 14 root 870 1424 15 root 870 1424 16 root 870 1424 17 root 870 1424 18 root 870 1424 19 root 870 1424 20 root 870 1424 21 root 870 1424 22 root 870 1424
Then compare with the running Aerospike process:
root@asd70-1:/# ps ax | grep asd
1424 ? Ssl 0:01 /usr/bin/asdIf Aerospike is actively using these segments, lpid will often match the running asd PID.
cpid may reflect an earlier Aerospike process that originally created the segment.
The following bash script can be used to compare resident memory with the total allocated Aerospike shared memory based on segment size:
cat ./getshmem.sh
#!/bin/bash
# --- Configuration ---
# Aerospike SHM Key Prefixes (excluding the initial '0x'):
# ae: Primary Index (PI)
# a2: Secondary Index (SI)
# ad: Data in Memory (D)
AEROSPIKE_KEY_PREFIXES="ae|a2|ad"
# Get the system memory page size in bytes
PAGE_SIZE_BYTES=$(getconf PAGE_SIZE 2>/dev/null)
if [[ -z "$PAGE_SIZE_BYTES" || "$PAGE_SIZE_BYTES" == 0 ]]; then
# Fallback to 4096 bytes if getconf fails
PAGE_SIZE_BYTES=4096
fi
# --- 1. Calculate Total ALLOCATED Size for Aerospike Segments (from ipcs -m) ---
TOTAL_ALLOCATED_BYTES=0
# Filter ipcs -m output for Aerospike keys and sum the "bytes" column (column 5)
AEROSPIKE_SEGMENTS=$(ipcs -m 2>/dev/null | grep -E "^0x($AEROSPIKE_KEY_PREFIXES)")
if [ -n "$AEROSPIKE_SEGMENTS" ]; then
TOTAL_ALLOCATED_BYTES=$(echo "$AEROSPIKE_SEGMENTS" | awk '{sum += $5} END {print sum}')
fi
TOTAL_ALLOCATED_MB=$(awk "BEGIN { printf \"%.2f\", $TOTAL_ALLOCATED_BYTES / 1024 / 1024 }")
# --- 2. Calculate Total RESIDENT Size System-Wide (from ipcs -u) ---
PAGES_RESIDENT=0
# Get the "pages resident" line from ipcs -u
PAGES_RESIDENT_LINE=$(ipcs -u 2>/dev/null | grep "pages resident")
if [ -n "$PAGES_RESIDENT_LINE" ]; then
# FIX: Extract the number of resident pages, which is the LAST word ($NF).
PAGES_RESIDENT=$(echo "$PAGES_RESIDENT_LINE" | awk '{print $NF}')
fi
# Calculate total resident bytes
TOTAL_RESIDENT_BYTES=$(awk "BEGIN { print $PAGES_RESIDENT * $PAGE_SIZE_BYTES }")
TOTAL_RESIDENT_MB=$(awk "BEGIN { printf \"%.2f\", $TOTAL_RESIDENT_BYTES / 1024 / 1024 }")
# --- 3. Report ---
echo "--- Aerospike Shared Memory Summary (System-Wide) ---"
echo "System Page Size: $(awk "BEGIN { print $PAGE_SIZE_BYTES / 1024 }") KB"
echo "--------------------------------------------------------"
echo "Aerospike Segments Found: $(echo "$AEROSPIKE_SEGMENTS" | wc -l) (0x$AEROSPIKE_KEY_PREFIXES)"
echo ""
echo "TOTAL ALLOCATED (MB): $TOTAL_ALLOCATED_MB MB"
echo "SYSTEM RESIDENT (MB): $TOTAL_RESIDENT_MB MB"
echo "--------------------------------------------------------"
echo "Note: The 'SYSTEM RESIDENT' value is for ALL shared memory segments on the system,"
echo "not just Aerospike, but provides an upper bound and confirmation of resident pages."
Notes
Aerospike does not auto-release shared memory segments.
The memory Arenas will stay allocated and will not get released by Aerospike until a cold start.
Any storage engine memory segments will not be released on a cold start.
You will see differing cpids (Creator Pid's) for a coldstart.
root@asd70-1:/# ipcs -mp ------ Shared Memory Creator/Last-op PIDs -------- shmid owner cpid lpid 15 root 870 1732 16 root 870 1732 17 root 870 1732 18 root 870 1732 19 root 870 1732 20 root 870 1732 21 root 870 1732 22 root 870 1732 27 root 1732 1732 root@asd70-1:/# ps ax | grep asd 1732 ? Ssl 0:01 /usr/bin/asd --cold-start
Storage engine memory should use by default stripes of 8 shared memory segments, unless files/devices are specified for file backed storage, at which point you will get a stripe count matching the number of devices/files you have specified.