How to Check Harddrive information

Here are several commands that will allow us to check information regarding hard drives.

fdisk: for hdd sizes/partitions

fdisk is useful for checking the sizes and partitions of hard drives that are connected to a host. Physical hard disks are usually given a name of /dev/sd[a-z]. Using the command as root:

fdisk -l 

will provide us information regarding all the physical hard disks that are located on the host and all the partitions that reside on those disks. Non-physical disks are included in the output too.

You will see devices such as:

Disk /dev/sdc                                 // physical hard disk
Disk /dev/md[0-10]                            // software raid volume
Disk /dev/mapper/vg_system-lv_root            // logical volume

cat /proc/scsi/scsi for actual models of HDDs

We have a variety of different HDD models we use from various companies. We'll often encounter an HDD we find to be reliable or a model we want to avoid altogether for the rest of our lives. Since
we don't always have physical access to the interior of a machine to check the HDD models, the easiest way to check what model is in a host is to check under /proc/scsi/scsi.

[root@he bulk]# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
 Vendor: ATA      Model: Samsung SSD 840  Rev: BB6Q
 Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
 Vendor: ATA      Model: Samsung SSD 840  Rev: BB6Q
 Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
 Vendor: ATA      Model: WDC WD1000CHTZ-0 Rev: 6A01
 Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi3 Channel: 00 Id: 00 Lun: 00
 Vendor: ATA      Model: WDC WD1000CHTZ-0 Rev: 6A01
 Type:   Direct-Access                    ANSI  SCSI revision: 05

cat /sys/block/sd*/queue/rotational check if HDD/SSD

If you're not sure whether the disks on your system are HDDs or SSDs, do the simple command:

cat /sys/block/sd*/queue/rotational

The output is in descending order starting from the first disk detected, usually sda.

This will output either 0 or 1.

0 == SSDs
1 == HDDs

Example:

# My first disk is an SSD
[root@he fast]# cat /sys/block/sda/queue/rotational 
0

# I have two SSDs, /dev/sda & /dev/sdb, and two HDDs /dev/sdc & /dev/sdd
[root@he fast]# cat /sys/block/sd*/queue/rotational 
0
0
1
1