How To Plan For Memory Expansion On a Linux Host

Author: Vivek Gite Last updated: July 24, 2008 5 comments

This is an user contributed article.

What is the current total RAM used in the system?

This can be obtained using free command or from the /proc/meminfo file as shown below. In this example, the current RAM is 1GB.
# free
Sample output:

             total       used       free     shared    buffers     cached
Mem:       2074016    2002592      71424          0     480908     937296
-/+ buffers/cache:     584388    1489628
Swap:      1951888      79116    1872772

You can also display memory ram, info using /proc file, enteR:
# grep MemTotal /proc/meminfo
Sample output:

MemTotal:      1034624 kB

What is the maximum RAM supported by the system?

You can use dmidecode command to query all memory related information from the system DMI table. In this example, the maximum RAM supported by the system is 8 GB as shown below.

# dmidecode -t 16
Sample output:

# dmidecode 2.9
SMBIOS 2.3 present.
Handle 0x1000, DMI type 16, 15 bytes
Physical Memory Array
Location: System Board Or Motherboard
Use: System Memory
Error Correction Type: Multi-bit ECC
Maximum Capacity: 8 GB
Error Information Handle: Not Provided
Number Of Devices: 4

How many memory slots are available for expansion?

# dmidecode -t 17 | grep Size
Sample output:

        Size: 512 MB
        Size: 512 MB
        Size: No Module Installed
        Size: No Module Installed

References:

dmidecode can also be used to identify details about several other hardware related information. dmidecode command reads the systems DMI table for the hardware and BIOS information. DMI stands for Desktop Management interface and SMBIOS stands for System Management BIOS.

Distributed Management Task Force maintains the DMI and SMBIOS specification:

DMI Specification
SMBIOS Specification
man pages – dmidecode, free and proc

🐧 Get the latest tutorials on SysAdmin, Linux/Unix, Open Source & DevOps topics via:

RSS feed or Weekly email newsletter
Share to Twitter • Facebook • 5 comments... add one ↓

Category	List of Unix and Linux commands
File Management	cat
Firewall	Alpine Awall • CentOS 8 • OpenSUSE • RHEL 8 • Ubuntu 16.04 • Ubuntu 18.04 • Ubuntu 20.04
Network Utilities	dig • host • ip • nmap
OpenVPN	CentOS 7 • CentOS 8 • Debian 10 • Debian 8/9 • Ubuntu 18.04 • Ubuntu 20.04
Package Manager	apk • apt
Processes Management	bg • chroot • cron • disown • fg • jobs • killall • kill • pidof • pstree • pwdx • time
Searching	grep • whereis • which
User Information	groups • id • lastcomm • last • lid/libuser-lid • logname • members • users • whoami • who • w
WireGuard VPN	CentOS 8 • Debian 10 • Firewall • Ubuntu 20.04