Re: [gentoo-embedded] profiles for reduced disk usage

[Joshua ChaitinPollak]

Here's a response from a co-worker who has done some work on his EEE pc:

> Interesting stuff. As I understand it, with the Asus I've read that
> they've basically leveraged a write-balancing algorithm at the flash
> firmware level so that they fairly evenly distribute updates across
> the flash. So, bottom line, Asus doesn't worry too much about burn-
> in. They even ship with a writable ext3 partition, which would be
> really detrimental to disk due to the "duplicate write" overhead of
> continuous journaling (presumably in a fixed area of the disk?) if
> it weren't for the balancing logic.
>
> W.r.t. keeping log size down, I think Asus's build of Xandros has
> turned off a bunch of debug-level logging within most of their
> packages (at build time?) and as such doesn't really demand much
> disk for logging operations, etc.
>
> Same may apply to a Gentoo install - compile your stuff to not log
> at debug level (or turn off in syslog?) and you should be fine...
>
> One thing that I did observe when I started using external ext2/ext3
> partitions on the SD card slot was extremely lethargic writes. This
> was due to the fact that SD cards with ext2/ext3 partitions were
> being mounted with the 'sync' flag. From what I have read, this is
> extremely slow and extremely detrimental to flash. This is because
> every byte would be written individually, but due to the way flash
> works, you write a block at once. So, say the block size is 192
> bytes... To write 192 bytes with sync on could cause 192 flashes of
> the block (or some fraction/multiple of 192). With async enabled
> (sync not enforced) the OS is able to cache up some data before
> writing, dramatically increasing the likelihood that it will have
> enough data to fill the block in 1 single write operation.
>
> So, another tip for Gentoo users - make sure any ext2/ext3 flash
> partitions are mounted async (default) - not with the sync flag set
> like Xandros does by default with the SD card slot...
>
> -Andrew

On Apr 17, 2008, at 11:12 AM, Christian Bricart wrote:

> Joshua ChaitinPollak wrote:
>> [..]
>> I don't know how you'd handle things like Firefox's cache, I don't
>> know any way to reduce its writes or redirect them out of your
>> profile.
>
> http://www.mozilla.org/catalog/end-user/customizing/briefprefs.html
> http://kb.mozillazine.org/Browser.cache.disk.parent_directory
>
> drop a file in /usr/lib/mozilla-firefox/defaults/pref/ with content
> like:
>
> +---
> | pref("browser.cache.disk.parent_directory", "/tmp");
> +---
>
> or even:
>
> +---
> | pref("browser.cache.disk.enable", false);
> +---
>
> Christian
>
>
> --
> gentoo-embedded@l.g.o mailing list
>
>

-- 
Joshua ChaitinPollak | Software Engineer
Kiva Systems, Inc., 225 Wildwood Ave, Woburn, MA 01970