Update Samsung SSD 840 EVO firmware on Zotac Linux server (poor read performance of old files).

My Samsung SSD 840 EVO was suffering from the apparently well known problem that 'old' files (files which have been written a long while ago and not touched since) had slow read transfer rates (as low as 5 MBytes/s in places, 29 MBytes/s for some big files I had).

I have a Zotac server without a CD drive, so I needed to run the Samsung Performance Restauration tool. I used the DOS / Mac variant which is a DOS bootable disk which contains the update tool. The easiest way to prepare the USB stick is NOT to use the USB zip provided by Samsung but to use the *.iso file (Samsung_Performance_Restoration.iso) instead:

- Mount the ISO file and get the file ISOLINUX/BTDSK.IMG from it.
- dd the BTDSK.IMG directly onto a USB stick
- boot from the USB stick and follow the instructions

On my Zotac machine when booting from this USB stick I got a couple of broken error messages about not being able to boot from device XYZ, but it booted OK from the stick after a couple of seconds.

The performance restauration procedure took 4.5h for a 1TB SSD (60% full) and about 15h for another 1TB SSD (95% full), so expect this to take some time.

Both SSDs were not erased by the procedure.

Avoid hang of headless Zotac server on Ubuntu Linux reboot. (How to disable the graphical console for grub and the Linux kernel.)

My Zotac server did not reboot without a monitor attached. Booting from power-up did work ok. The graphical console of grub seemed to be the problem. Since I do not use the monitor output at all not setting any graphics mode at all and using the 80x25 default console is fine for me. This is how to disable the graphical grub console:

Edit /etc/default/grub

Uncomment this line:
GRUB_TERMINAL=console

In addition I disabled setting any graphics mode on the Linux kernel and setting the timeout to 1 second.

My /etc/default/grub  file now looks like this:

GRUB_DEFAULT=0

GRUB_HIDDEN_TIMEOUT_QUIET=true

GRUB_TIMEOUT=1

GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`

GRUB_CMDLINE_LINUX_DEFAULT="text nomodeset"

GRUB_CMDLINE_LINUX=""

GRUB_TERMINAL=console

Reboot time: The time between pressing enter after 'reboot' and being logged in again with ssh is 25s.