Backup drive shows as sda (instead of sdb)

Questions about other topics - please check if your question fits better in another category before posting here
Forum rules
Before you post please read how to get help
Post Reply
Netherprovinc3
Level 3
Level 3
Posts: 165
Joined: Mon Feb 04, 2019 9:29 pm

Backup drive shows as sda (instead of sdb)

Post by Netherprovinc3 » Sun Aug 25, 2019 9:49 pm

I have an external drive that I use for backups. The drive is a Sata III HDD in an enclosure and is formatted with the GUID partition table. Initially, I used the drive for File History backups (the Windows equivalent of Back in Time). Recently, however, I started using it for Back in Time backups (on a newly created partition on that drive, removed a Windows partition to do so).

When I open gparted, the drive shows as sda. I would have thought that my internal drive shows as sda, and that this drive should show as sdb or sdc (I also have a small USB stick plugged into my computer). Is this potentially a problem?

I'll also add that one time I accidentally booted from an external drive with Linux installed and in the UEFI interface it shows two "ubuntu" choices in the boot options (at least the last time that I checked).
Linux Mint 19.1 Cinnamon

deck_luck
Level 3
Level 3
Posts: 190
Joined: Mon May 27, 2019 6:57 pm
Location: here

Re: Backup drive shows as sda (instead of sdb)

Post by deck_luck » Mon Aug 26, 2019 12:11 am

Usually, the sda short name is associated with the lowest SATA port disk found during the kernel initial scanning and sizing. However, Linux never guarantees the short name will be persistent across boots, and for this reason you may have noticed the UUID= entries in your /etc/fstab. The UUID will always be the same across boots, so it is considered a persistent reference method. In the Linux Enterprise environment this can become a major concern when adding new SAN LUNs.

On a laptop with one disk, Linux in most cases will discover /dev/sda. On a desktop with more than one disk, Linux will usually reference the disk on SATA port 0 with the /dev/sda short name. Likewise, SATA port 1 will be /dev/sdb, and SATA port 2 will be /dev/sdc. Generally, the USB external drive will come after all of the internal drives.

It might help if you post the output from the following command:

Code: Select all

lsblk -S -o+size
💡Give a man a fish, and you feed him for a day. Teach a man to fish, and you feed him for a lifetime. ✝️

Netherprovinc3
Level 3
Level 3
Posts: 165
Joined: Mon Feb 04, 2019 9:29 pm

Re: Backup drive shows as sda (instead of sdb)

Post by Netherprovinc3 » Mon Aug 26, 2019 11:09 am

Right now the drives show as you describe
sda - internal sata drive
sdb - external drive
sdc - usb thumb drive

The only thing that has changed is that I disconnected the drive (to connect it to another computer) and then reconnected it. Also, I rebooted the computer.

Should I still run the command that you mention? Or see if it reverts to having the external drive as sda before doing that?
Linux Mint 19.1 Cinnamon

deck_luck
Level 3
Level 3
Posts: 190
Joined: Mon May 27, 2019 6:57 pm
Location: here

Re: Backup drive shows as sda (instead of sdb)

Post by deck_luck » Mon Aug 26, 2019 1:40 pm

Boot, reboot, and disconnect etc then check the drive short names.
Experiment and see how it responds. I like it.
💡Give a man a fish, and you feed him for a day. Teach a man to fish, and you feed him for a lifetime. ✝️

Netherprovinc3
Level 3
Level 3
Posts: 165
Joined: Mon Feb 04, 2019 9:29 pm

Re: Backup drive shows as sda (instead of sdb)

Post by Netherprovinc3 » Thu Aug 29, 2019 7:54 am

I have not been checking the drive listings on every boot. But, I just installed new ram and I see that the drives are back to the way they were when I wrote the OP.
Here is the output from the command

Code: Select all

NAME HCTL       TYPE VENDOR   MODEL             REV TRAN     SIZE
sda  0:0:0:0    disk WDC WD10 EZEX-60M2NA0     8104 usb    931.5G
sdb  3:0:0:0    disk ATA      KINGSTON SA400S3 5A   sata   223.6G
sr0  1:0:0:0    rom  hp       CDDVDW SH-216DB  HH20 sata    1024M
Linux Mint 19.1 Cinnamon

Post Reply

Return to “Other topics”