How do I find out what hard disks are in the system?

Question

I need to know what hard disks are available, including ones that aren't mounted and possibly aren't formatted. I can't find them in dmesg or /var/log/messages (too much to scroll through). I'm hoping there's a way to use /dev or /proc to find out this information, but I don't know how. I am using Linux.

Solution 1

This is highly platform-dependent. Also different methods may treat edge cases differently (“fake” disks of various kinds, RAID volumes, …).

On modern udev installations, there are symbolic links to storage media in subdirectories of /dev/disk, that let you look up a disk or a partition by serial number (/dev/disk/by-id/), by UUID (/dev/disk/by-uuid), by filesystem label (/dev/disk/by-label/) or by hardware connectivity (/dev/disk/by-path/).

Under Linux 2.6, each disk and disk-like device has an entry in /sys/block. Under Linux since the dawn of time, disks and partitions are listed in /proc/partitions. Alternatively, you can use lshw: lshw -class disk.

Linux also provides the lsblk utility which displays a nice tree view of the storage volumes (since util-linux 2.19, not present on embedded devices with BusyBox).

If you have an fdisk or disklabel utility, it might be able to tell you what devices it's able to work on.

You will find utility names for many unix variants on the Rosetta Stone for Unix, in particular the “list hardware configuration” and “read a disk label” lines.

Solution 2

lsblk will list all block devices. It lends itself well to scripting:

$ lsblk -io KNAME,TYPE,SIZE,MODEL
KNAME TYPE   SIZE MODEL
sda   disk 149.1G TOSHIBA MK1637GS
sda1  part  23.3G 
sda2  part    28G 
sda3  part  93.6G 
sda4  part   4.3G 
sr0   rom   1024M CD/DVDW TS-L632M

lsblk is present in util-linux package and is thus far more universal than proposed alternatives.

Solution 3

How about

lshw -class disk

Solution 4

hwinfo helps:

> hwinfo --disk
21: IDE 00.0: 10600 Disk                                        
[Created at block.245]
Unique ID: 3OOL.8MZXfAWnuH8
Parent ID: w7Y8.1T_0outZkp6
SysFS ID: /class/block/sda
SysFS BusID: 0:0:0:0
SysFS Device Link: /devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0
Hardware Class: disk
Model: "Hitachi HTS54322"
Vendor: "Hitachi"
Device: "HTS54322"
Revision: "ESBO"
Driver: "ahci", "sd"
Driver Modules: "ahci"
Device File: /dev/sda
Device Files: /dev/sda, /dev/disk/by-id/ata-Hitachi_HTS543225A7A384_E2021342GEPG4J, /dev/disk/by-id/scsi-SATA_Hitachi_HTS5432_E2021342GEPG4J, /dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0, /dev/disk/by-id/wwn-0x5000cca614c6395e
Device Number: block 8:0-8:15
BIOS id: 0x80
Geometry (BIOS EDD): CHS 484521/16/63
Size (BIOS EDD): 488397168 sectors
Geometry (BIOS Legacy): CHS 1023/255/63
Drive status: no medium
Config Status: cfg=new, avail=yes, need=no, active=unknown
Attached to: #17 (SATA controller)
> hwinfo --block --short
disk:                                                           
  /dev/sda             Hitachi HTS54322
partition:
  /dev/sda1            Partition
  /dev/sda2            Partition
  /dev/sda3            Partition
  /dev/sda4            Partition
  /dev/sda5            Partition

Solution 5

@Giles says this is highly platform-dependent. Here's one such example.

I'm running a CentOS 5.5 system. This system has 4 disks and a 3ware RAID controller.

In my case, lshw -class disk, cat /proc/scsi/scsi and parted --list shows the RAID controller (3ware 9650SE-4LP). This doesn't show the actual disks:

only shows the 3ware RAID controller which provides the /dev/sda volume:

# lshw -class disk
  *-disk                  
       description: SCSI Disk
       product: 9650SE-4LP DISK
       vendor: AMCC
       physical id: 0.0.0
       bus info: scsi@0:0.0.0
       logical name: /dev/sda

# cat /proc/scsi/scsi 
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: AMCC     Model: 9650SE-4LP DISK  Rev: 4.06
  Type:   Direct-Access                    ANSI SCSI revision: 05

# parted --list

Model: AMCC 9650SE-4LP DISK (scsi)
Disk /dev/sda: 2000GB

In order to see the disks which lie underneath, I had to install the tw_cli utility from 3ware, and ask the controller itself.

# tw_cli info c0
...

VPort Status         Unit Size      Type  Phy Encl-Slot    Model
------------------------------------------------------------------------------
p0    OK             u0   931.51 GB SATA  0   -            WDC WD1002FBYS-02A6 
p1    OK             u0   931.51 GB SATA  1   -            WDC WD1002FBYS-02A6 

View more solutions

Comments

[Admin]

The original question didn't specify any particular unix variant, and hardware management is obviously highly variant-dependent.

[Admin]

@gilles yeah I was at work when I wrote it, so I clarified after I got home and thought about it.

[Admin]

Depending on what you're doing, udisks.

[Admin]

I found a useful page describing many common hardware commands with a search on Google. The disk drive ones include lshw (List Hardware), hwinfo (Hardware Information), lsscsi (List scsi devices), lsusb (List usb buses/devices), lsblk (List block devices), fdisk -l and mount. More information at binarytides.com/linux-commands-hardware-info.

[xenoterracide]

not bad... I'll double check it when I get off, I'm sure it works... unfortunately it's (lshw) not installed on the server, and I suspect the answer will be we're not installing it.

[Michael Mrozek]

Ooo; that Rosetta Stone site is excellent

[laebshade]

Use fdisk -l /dev/sd? or fdisk -l /dev/hd? to avoid bring in dm devices.

[NicBright]

It should be noted that the smartctl way even works on Cygwin, +1! Just loop over possible device names and see if smartctl returns that the drive supports SMART.

[André van Schoubroeck]

For some reason, lshw does not list hard disks.

[Anthon]

This is off by 500% on one of my systems (Ubuntu 12.04) and by 200% on another system.

[Volker Siegel]

When not run as root, it lists no disks, but also gives no error.

[Lahi2010]

If you only need the physical disks, use lsblk -d, -d means no dependency message listed.

[tuk0z]

Indeed =) $ lsblk -ido KNAME,TYPE,SIZE,MODEL (part of util-linux which is part of base on Arch) instantly gives the information requested, and without the need to be root. Note that it provides the Device model, not Model Family. smarctl -i /dev/<device> advised by Skippy did it, eg: "Model Family: Seagate Barracuda 7200.12" (missing from lsblk -ido: "disk 465,8G ST3500418AS").

[Anthony]

bash: lshw: command not found

[Steven Lu]

skips NVMe SSDs

[Jürgen A. Erhard]

"number of block devices" was not the question.

[João Pimentel Ferreira]

sudo lshw -class disk made my day, simple and intuitive output.

[Martin]

The cleaner way would be to use lsblk --nodeps. (Add --noheadings to get exactly your output.)