Ever find yourself having to look into the particulars of your servers' hardware? Maybe you go scrounging for the original invoice or for some email you were sent several years ago or the quote that was generated when you were about to purchase it? Well, stop, there's an alternative that you're probably going to like quite a bit. You can get your hardware to tell you about itself. Just use a command called dmidecode.
The name "dmidecode" might not ring any bells, but the "dmi" part of the name stands for "Desktop Management Interface". It's an API that allows you to gather information about the your system's underlying hardware. The command is designed to work on any Linux system as it was originally designed by a consortium -- the Desktop Management Task Force -- for gathering information and configuring systems.
The dmidecode command gets its data from the DMI tables stored in memory and presents it in a human readable format. The commands that you will probably like the most are commands like these:
$ sudo dmidecode | grep Vendor
Vendor: Dell Inc.
$ sudo dmidecode -t system | grep Product
Product Name: PowerEdge R710
These commands show that the system that Linux is running on is a Dell PowerEdge R710. And, while piping the dmidecode's output to grep might seem a bit "much", you should note that the command generates quite a bit of output -- often more than a thousand lines. Looking for specific lines will probably save you quite a bit of time.
# dmidecode | wc -l 1046
Finding the serial number of the system:
# dmidecode | grep "Serial Number" | head -n1
Serial Number: FWZPXQ1
Finding out something about the CPUs:
# dmidecode | grep CPU
Socket Designation: CPU1
Version: Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
Socket Designation: CPU2
Version: Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
CPU.Socket.1
CPU.Socket.2
Determining if the system has a RAID array:
# dmidecode | grep RAID
Description: Integrated RAID Controller
Integrated RAID
You can also learn about specific components if you know their type identifiers. For example, processors are type 4, so let's pull up information on the processors (much more than we looked at in the command above).
# dmidecode -t 4 | head -53
# dmidecode 2.7
SMBIOS 2.6 present.
Handle 0x0400, DMI type 4, 40 bytes.
Processor Information
Socket Designation: CPU1
Type: Central Processor
Family: Xeon
Manufacturer: Intel
ID: C2 06 02 00 FF FB EB BF
Signature: Type 0, Family 6, Model 44, Stepping 2
Flags:
FPU (Floating-point unit on-chip)
VME (Virtual mode extension)
DE (Debugging extension)
PSE (Page size extension)
TSC (Time stamp counter)
MSR (Model specific registers)
PAE (Physical address extension)
MCE (Machine check exception)
CX8 (CMPXCHG8 instruction supported)
APIC (On-chip APIC hardware supported)
SEP (Fast system call)
MTRR (Memory type range registers)
PGE (Page global enable)
MCA (Machine check architecture)
CMOV (Conditional move instruction supported)
PAT (Page attribute table)
PSE-36 (36-bit page size extension)
CLFSH (CLFLUSH instruction supported)
DS (Debug store)
ACPI (ACPI supported)
MMX (MMX technology supported)
FXSR (Fast floating-point save and restore)
SSE (Streaming SIMD extensions)
SSE2 (Streaming SIMD extensions 2)
SS (Self-snoop)
HTT (Hyper-threading technology)
TM (Thermal monitor supported)
PBE (Pending break enabled)
Version: Intel(R) Xeon(R) CPU X5650 @ 2.67GHz
Voltage: 1.2 V
External Clock: 6400 MHz
Max Speed: 3600 MHz
Current Speed: 2666 MHz
Status: Populated, Enabled
Upgrade: <OUT OF SPEC>
L1 Cache Handle: 0x0700
L2 Cache Handle: 0x0701
L3 Cache Handle: 0x0702
Serial Number: Not Specified
Asset Tag: Not Specified
Part Number: Not Specified
That's a lot of information and probably more than most of us want to know, but for some people, this level of detail might be very important. And note that this output is only showing the first of the two CPUs to keep it from dominating this post.
And, no, you don't have to memorize the device types. You'll find a table like this in the dmidecode command's man page or you can reference this nice little post every time you get curious (I'd suspect the man page is a tad easier to find).
Type Information
----------------------------------------
0 BIOS
1 System
2 Base Board
3 Chassis
4 Processor
5 Memory Controller
6 Memory Module
7 Cache
8 Port Connector
9 System Slots
10 On Board Devices
11 OEM Strings
12 System Configuration Options
13 BIOS Language
14 Group Associations
15 System Event Log
16 Physical Memory Array
17 Memory Device
18 32-bit Memory Error
19 Memory Array Mapped Address
20 Memory Device Mapped Address
21 Built-in Pointing Device
22 Portable Battery
23 System Reset
24 Hardware Security
25 System Power Controls
26 Voltage Probe
27 Cooling Device
28 Temperature Probe
29 Electrical Current Probe
30 Out-of-band Remote Access
31 Boot Integrity Services
32 System Boot
33 64-bit Memory Error
34 Management Device
35 Management Device Component
36 Management Device Threshold Data
37 Memory Channel
38 IPMI Device
39 Power Supply
You'll probably find that dmidecode knows a lot more about your servers' hardware than you'd ever want to understand, but the command makes it easy to fetch information when yoiu need it and doesn't require you to go scrounging through your file cabinet or your old email.
And you don't have to be anywhere near the systems to find the information that you need.
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