With SSD arriving more and more in our lives it is natural to find it on linux servers too.
Not working with SSD in this area much, haven't found much interest of finding ssd related things in Linux so far.
So, nowadays one can wonder wondering: how would I know if my disks in Linux are SSD or not?
A valid response would be: close the system, open it up and see what disk you have there :)))
But what if this is a linux server far far away? You need to be able to find out these things from OS level.
So, without too much bla bla (I like to bla bla sometimes), it is fairly simple to find out this.
I have this virtual machine running in a nice mac mini with ESXI on it and one datastore is SSD. I have 3 disks in this machine and one is SSD: /dev/sdb.
18:06:12 root@eeny:~# fdisk -l /dev/sd? | grep "^Disk /" Disk /dev/sda: 1 TiB, 1099511627776 bytes, 2147483648 sectors Disk /dev/sdb: 30 GiB, 32212254720 bytes, 62914560 sectors Disk /dev/sdc: 3.64 TiB, 4000787029504 bytes, 7814037167 sectors
There is in /sys a place, /sys/block/sd?/queue/rotational, where if you get 0 is SSD and 1 is normal disk. Rotational means disk that spins :)
So as it is clearly stated below, /dev/sdb is SSD! Hooray :)
[/i]NOTE: if the ssd device is connected via USB, sometimes this method will not see it ass "not rotational".[/i]
18:06:16 root@eeny:~# cat /sys/block/sda/queue/rotational 1 18:06:52 root@eeny:~# cat /sys/block/sdb/queue/rotational 0 18:06:55 root@eeny:~# cat /sys/block/sdc/queue/rotational 1
There is also a way to achieve this result with lsblk command:
Again, sdb = 0 which means SSD.
18:12:20 root@eeny:~# lsblk -d -o name,rota NAME ROTA sda 1 sdb 0 sdc 1 sr0 1
Still not satisfied?!! OK...
You can get this also with smartmontools :P
Again, sdb is SSD. Incredible!
HINT: virtual disks do not show usually rotational state if the disk is not SSD. So, /dev/sda and /dev/sdb are virtual disks but because /dev/sdb is marked by the host as SSD, it contains this value.
18:12:22 root@eeny:~# smartctl -a /dev/sda | grep 'Rotation Rate' 18:14:18 root@eeny:~# smartctl -a /dev/sdb | grep 'Rotation Rate' Rotation Rate: Solid State Device 18:14:22 root@eeny:~# smartctl -a /dev/sdc | grep 'Rotation Rate' Rotation Rate: 5980 rpm
With lshw command
There is another way to check if you have ssd or not, if the disk is not virtual (e.g. provided by vmware or virtualbox or etc.).
The command lshw will scan for all disks and display their information including name hardware path. This is useful information.
15:26:18 root@minivm:~# lshw -short -C disk H/W path Device Class Description ================================================================ /0/100/11/3/0.0.0 /dev/cdrom disk VMware SATA CD00 /0/100/15/0/0.0.0 /dev/sda disk 32GB Virtual disk /0/100/15/0/0.1.0 /dev/sdb disk 1099GB Virtual disk /0/100/15.2/0/1/1/0.0.0 /dev/sdc disk 120GB SA400S37120G /0/100/15.2/0/1/2/0.0.0 /dev/sdd disk 120GB 650 /0/100/15.2/0/1/3/0.0.0 /dev/sdf disk 4TB 2135 /0/100/15.2/0/1/4/1/0.0.0 /dev/sdg disk 4TB 2135 /0/100/15.2/0/1/4/2/0.0.0 /dev/sdh disk 4TB 2135 /0/100/15.2/0/1/4/3/0.0.0 /dev/sdi disk 4TB 2135
Also lsscsi command can show you similar information like lshw:
15:29:54 root@minivm:~# lsscsi [0:0:0:0] disk VMware Virtual disk 2.0 /dev/sda [0:0:1:0] disk VMware Virtual disk 2.0 /dev/sdb [3:0:0:0] cd/dvd NECVMWar VMware SATA CD00 1.00 /dev/sr0 [63:0:0:0] disk KINGSTON SA400S37120G 8101 /dev/sdc [64:0:0:0] disk ADATA SU 650 XD0R /dev/sdd [65:0:0:0] disk ASMT 2135 0 /dev/sdf [66:0:0:0] disk ASMT 2135 0 /dev/sdg [67:0:0:0] disk ASMT 2135 0 /dev/sdh [68:0:0:0] disk ASMT 2135 0 /dev/sdi
All this info can be shown only if the method used for connecting the disk is made to do so.
As example, some USB racks do not have the capability to send to the OS the disk information so they will be shown with nothing or with the rack's information (e.g. ASMT 2135 is not the disk info but the rack to which the disk is connected).
Ok, I am done. If you are not satisfied there is nothing else I can do here...