Worries about write limits for Compact Flash cards

Forum: HD Install
Topic: Worries about write limits for Compact Flash cards
started by: JCCyC

Posted by JCCyC on May 13 2005,17:40

I just installed DSL on a CompactFlash card (with an IDE adapter) like this one: < http://www.sandisk.com/retail/cf.asp > with no problems whatsoever. I worry, though, about the rewrite limits such devices have. Some sectors of the "disk" get rewritten lots and lots of times.

I know there's a filesystem in Linux designed for this purpose -- it distributes the writes so no sector gets written too many more times than average. Is this available -- JFFS? Does it work in 2.4 kernels too? Is it available in the default DFS kernel (if not, I'll compile a new kernel, no problem) Anyone has experience with such a thing?

Posted by cbagger01 on May 13 2005,22:25

DSL contains built-in support for accessing jffs and jffs2 file systems.

However, you will need mkfs tools to be installed if you wish to create/format a new file system from scratch.

You can install apt or synaptic and apt-get:

mtd-tools

for this support.

If you want the newer version of mtd-tools, you will need to edit your /etc/apt/sources.list file and uncomment the "testing" line and add a comment (#) to the "stable" line. Then run apt-update

However, you will not need to do this if you choose to install DSL via the "frugal install" method, because DSL frugal uses a read-only compressed filesystem and a ramdisk so it does not perform constant writes to your flash device.

Posted by JCCyC on May 13 2005,23:36

Quote (cbagger01 @ May 13 2005,18:25)

Pardon the ignorance, but what's the "frugal install" method? Fel free to whack me over the head and refer me to existing documentation if this question is too silly.

Posted by cbagger01 on May 14 2005,18:23

Hmm...

Maybe I am looking in the wrong place, but I cannot find a simple description of the frugal install concept in the documentation. Anyways, here goes:

DSL is designed to be a livecd. The cd-r disk contains a small linux distribution that is stored inside a compressed read-only file system, or cloop filesystem.

The cd also contains a flexible bootloader that works if your computer supports booting from a CDROM drive. The normal dsl livecd uses the ISOLINUX bootloader, but there is also a version that uses the SYSLINUX bootloader because some older computers don't work with ISOLINUX.

These bootloaders give you the ability to specify cheatcodes at boot time, which allows the user to customize the boot options depending on the computer that is being used (as a livecd, you can boot with an old computer, or later in the same day with a new computer and each can be told to boot in a different manner), and SYSLINUX is also used for the DSL boot floppy for computers that do not support CDROM booting.

Besides booting from the livecd, it is possible to copy the \knoppix\knoppix file (which contains the compressed filesystem) over to your hard drive and boot up from cd or floppy but run the operating system from the hard drive. This is called a "poormans install".

Because the filesystem is running from a harddrive instead of a cdrom drive, it is much faster than running from a livecd.

A "frugal install" is similar to the poormans install, except the additional step of LILO. The frugal install script (listed on the user menu) will also install the LILO bootloader to your hard drive, so you will no longer need a cd disk or a floppy disk in order to boot up DSL. Because the filesystem is still compressed and read-only, your operating system will not be making frequent writes to the hard drive (or "flash drive, in your case).

Finally, you can do a full hard drive install via script. This install will copy all of the individual files from the livecd over to a normal linux hard drive partition and then install lilo. This is similar to the normal installation process that is performed by most linux distributions like Red Hat, Slackware, etc. But this is not ideal install if you have a flash drive because the frequent writes (swap partition, log files, web browser cache, etc) will eventually cause your flash device to fail.

Hopefully this explanation is what you were looking for.