Ubuntu – Is putting swap on a USB2 flashdrive practical

13.10ssdswapusb-drive

After searching here, I found no direct answer to:

Is it practical to put swap on a USB Flash drive? I do not yet know if the teeny-tiny flash drive (Fit CZ33 ) I wish to use runs at high-speed (480 Mbps), full-speed (12 Mbps), or low-speed (1.5 Mbps), but am checking w/ SanDisk.

My intent is to reduce writes on the SSD for drive longevity; if the external flashdrive fails, I throw it away and get another.

Why? Because I just changed my ThinkPad R60 9459AT8 over to a Samsung SSD after maxing out the RAM at 3GB, set up trim after repartitioning with 20% free, removed swap, set swappiness to 0 and otherwise tuned up Xubuntu 13.10 for SSD. However, since it's not practical for me to add a mechanical HDD, I'd like to move the swap over to a Flashdrive which will always stay in the left side USB2 socket, for I'dather wear out a $12 flashdrive instead of a $180 SSD.

Why? Sometimes, I lose my WiFi connection until I reboot, plus rarely see slowdown, and I'd like to see if having swap again would help. I do watch a system monitor always in a panel and never exceed 30% free memory use, but would like to have swap without putting in on the SSD.

Yea, or nay?

And, does the size of the flashdrive make any difference: 8GB, 16GB or 32GB?

Best Answer

Flash drives are slower. My SSD is older and half the speed of newer systems and my system is all SATA2 and USB2.

sudo hdparm -t /dev/sdd4

older SSD drive: Timing buffered disk reads: 626 MB in 3.01 seconds = 208.20 MB/sec

Older 160GB rotating drive: Timing buffered disk reads: 212 MB in 3.01 seconds = 70.46 MB/sec

USB2 flash drive Timing buffered disk reads: 50 MB in 3.07 seconds = 16.26 MB/sec

Or my flash drive is only 10% as fast for reading as my slow SSD. And writes are notoriously slow on flash drives.

You can set swappiness to use RAM first.

cat /proc/sys/vm/swappiness
gksudo gedit /etc/sysctl.conf

Add this:

vm.swappiness=10

https://help.ubuntu.com/community/SwapFaq#What_is_swappiness_and_how_do_I_change_it.3F

There is the swapspace or dynamic swap manager. Looks like not maintained, but still in repository of 12.04.

sudo apt-get install swapspace

http://pqxx.org/development/swapspace/

Related Question