[Nottingham] FLASH vs HDD

Camilo Mesias camilo at mesias.co.uk
Wed Oct 31 13:03:14 GMT 2007


> Will I gain much of a speedup by using a USB flash drive for storing the
> OS and applications?

It's worth a try, because a real disk will spend time seeking around
before transferring data quickly whereas a flash drive will have no
seek time, even though it transfers data more slowly.

> I've seen a 4GB pendrive advertised at "x150" speed. What is that x150 of?!

Usually it means 150x faster than a first generation USB drive.

> Anyone tried this?

It's a feature in Vista, isn't it? I bet someone has tried it in
Linux. It wouldn't be that hard to find a directory with up to 4Gb of
non changing files in it, copy it all across to a USB drive, then
remount the drive over the top of the original files. Benchmarking it
and turning it into something that works from boot and survives the
USB stick being disconnected gracefully would be more of a challenge.

Apart from that it's possible to run a whole distro from a bootable
USB stick - just get one and copy a 'live CD' onto it (Fedora has a
page of instructions on this topic:
http://fedoraproject.org/wiki/FedoraLiveCD/USBHowTo )

Also the new Asus Eee PC that everyone is talking about has a 4Gb
flash drive as the boot disk.

> And what is the best fs for flash?

Flash disks emulate block devices so you don't need to do anything
really clever. In terms of tuning it would help if you can make the
clusters of the FS align with the clusters on the flash device (the
tricky bit being that information isn't easy to get). Also be sure to
turn off access time (ie. mount with the noatime option). Consider
ext2 rather than ext3 as journalling is an extra load on the flash
device. Most flash disks work fine with FAT!


More information about the Nottingham mailing list