Optimizing Linux Use On a USB Flash Drive?

Buckbeak writes "I like to carry my Linux systems around with me, on USB flash drives. Typically, SanDisk Cruzers or Kingston HyperX. I encrypt the root partition and boot off the USB stick. Sometimes, the performance leaves something to be desired. I want to be able to do an 'apt-get upgrade' or 'yum update' while surfing but the experience is sometimes painful. What can I do to maximize the performance of Linux while running off of a slow medium? I've turned on 'noatime' in the mount options and I don't use a swap partition. Is there any way to minimize drive I/O or batch it up more? Is there any easy way to run in memory and write everything out when I shut down? I've tried both EXT2 and EXT3 and it doesn't seem to make much difference. Any other suggestions?"

Comments

Did you read the faq?

[agristin]

make sure you are on USB 2.0- interface can kill you.

Also did you check the faq-

No seriously:

http://www.linux-usb.org/FAQ.html#i5

especially the section on:

Q: What is max_sectors and how should I use it?

A:For USB Mass Storage devices (that is, devices which use the usb-storage driver) max_sectors controls the maximum amount of data that will be transferred to or from the device in a single command. As the name implies this transfer length is measured in sectors, where a sector is 512 bytes (that's a logical sector size, not necessarily the same as the size of a physical sector on the device). Thus for example, max_sectors = 240 means that a single command will not transfer more than 120 KB of data.

Dave Jones suggestions for the eee900 might help

[Mr Z]

Dave Jones recently posted elsewhere his notes for improving things on the eee900. Several of the steps focus on getting proper performance out of the flash, and so would also apply to booting from a USB thumb drive or other flash media. Here's what he had to say:

Making the eee 900 series suck less.

Recently I've read about or spoken with a few people using Fedora on eeepc's who have been making some fairly big blunders without realising it. I've played with a few of these now, in their various incarnations.

The current one I've been carrying around is the 900 model with a whopping 20GB of flash. It's quite deceptive, because there are actually two SSDs in there (one 4GB, and one 16GB)

These ssds are also pretty damn awful performance-wise compared to the newer generation of SSDs, but short of opening it up and retrofitting something, there's not much that can be done. The tips below should at least make it more bearable.

• First off, don't use the default partitioning scheme.

  By default, anaconda will choose to use lvm, and make a contiguous volume out of the two SSDs. This idea is fail, because the two disks aren't the same, and run at different speeds.

  # hdparm -t /dev/sda

  /dev/sda:
  Timing buffered disk reads: 108 MB in 3.04 seconds = 35.57 MB/sec

  # hdparm -t /dev/sdb

  /dev/sdb:
  Timing buffered disk reads: 86 MB in 3.05 seconds = 28.20 MB/sec

  So, don't do that. Just create regular partitions, and make sure you put / on the faster of the two disks (the 4GB one), and leave the 16GB one for /home

• Next, the default filesystem will be ext3. You really don't want this.

  Given the journal is in a fixed location on disk, scribbling to it every time a file gets written is a great way to wear out the flash. Go with ext2. (Given that you've only got a few GB of flash anyway, a fsck doesn't take that long should you need to). Additionally, not having to write to the journal means that you're doing less IO, which is obviously a win when it's on such slow media.

• This should go without saying - no swap.

  Not only for the flash wear problem in the previous bullet, but also, because it's slow as all hell. If you find you run out of ram and get stuff oom-killed in this setup, well, you probably need to add more ram, or consider a real laptop.

• After installing, change the fstab so that everything gets mounted with noatime.

  Writes to the disk are just painful, so minimising them is the path to success here. It's doubtful that you'll be running anything on an eee that would actually care about atimes anyway.

With these points taken into consideration, the eee isn't a half-bad machine. I still wouldn't want to be building kernels and such on it, but it's perfectly usable for email and such whilst travelling.