Running an install from a flash drive

Question

I have created and used Ubuntu boot \ install DVDs and USB sticks.

I am installing in outfitting Ubuntu on an Optiplex 755: it is missing the HDD and its bracket. I have a 32GB USB Sandisk Cruzer I would like to use as a substitute for the HDD. The install shall not be a 'live-usb' where the iso is burned to the media for the purpose of testing Ubuntu / installing ubuntu.

If you have installed Ubuntu to a USB drive (not a live-usb), please indicate this and any observations \ lessons-learned.

The question is: if installed to a flash drive, are there any noticeable differences in performance vs a conventional spinning HDD?

Answer 1

Read/write speed may be lower unless using USB 3.0, but aside from that there shouldn't be too many notable differences. Ultimately it comes down to what hardware you're using, and may require some tinkering around - This is kind of one of those things you have to try for yourself, because every computer and every setup will yield different results. There shouldn't be any problem with the installation, and if its successful then you'll have a fully functional operating system in your pocket, bootable on any computer (Thumbs up for Ubuntu's amazing compatibility). Just turn off the computer, plug in the USB drive, tell the BIOS to boot from USB, and you'll have your OS and all your files on any computer you want. I definitely encourage you to try, because ultimately there's nothing to lose except for that which you don't have. As for your question, you'll have to try it for yourself to know for sure, because all hardware is different.

Answer 2

It works. I did it on the exact same PC ("lunchbox" format huh?).

As you might know, you can (should?) tweak the filesystem to avoid wearing out your flashdrive too soon, few tips:

in your /etc/fstab, add the "noatime" option to your main filesystems. For instance (replace the UUID with your own of course)

UUID=1218427f-e24b-4975-a025-d2db4264e796 /               ext4    noatime,errors=remount-ro 0       1

if you have, let's say 4GB or more RAM, try to avoid swap: decrease the swappiness kernel setting by adding something like

vm.swappiness=1

to /etc/sysctl.conf (sudo sysctl -p to reload some kernel settings without rebooting)

These are the basic tips, I didn't try much more tweaking as it was doing ok with my good old 755 running xubuntu. BTW, this 9 year old machine is still working, I finally added a refurbished 250 sata drive, still working almost night and day in my office.

Answer 3

Comparison between a Full install and a Persistent install to flash drive:

Advantages of a persistent install:

1) You can use the persistent pendrive to install Ubuntu to another computer.

2) A persistent install takes up less space on the pendrive.

3) You can reset the pendrive by overwriting the old casper-rw file with a new one.

4) The install to pendrive takes less time.

5) Slightly longer lifespan, a flash drive can take over 10000 writes, this can take years or decades.

Advantages of a Full install:

1) You can update and upgrade.

2) If you have problems or wish to modify, the solution is the same as with an internal install, (You can ask for help in these forums).

3) No ugly startup / install screen.

4) Better security, you can encrypt home folder.

5) You can use proprietary drivers.

6) Hibernation works.

7) A persistent install is limited to a 4GB casper-rw and a 4GB home-rw persistence file, to get more persistence requires persistence partitions, (possible with a mkusb persistent install)

8) Faster boot.

Note that once booted, both methods run at about the same speed.

I have used Full installs for many years but have been using a mkusb persistent install lately very fast using the run in RAM option.

Performance differences between Flashdrive install and HDD

A SSD would be fastest, then HDD, then USB3. If operating in RAM a flash drive should be fast enough.