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Author Topic: Reducing wear on flash and memory usage  (Read 1082 times)
virgesmith
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« on: December 12, 2009, 01:56:07 PM »

Hi

When I got an EEE 900 a while back I read some tips on some forum somewhere (can't remember where) about reducing wear on the SSD. I assume this is equally valid for the flash memory of the plug, however I didn't want to create too many tmpfs as the plug has less memory (and no swap).

So I got a fairly fast 4G SDHC card (Sandisk Extreme III, 15 on amazon) and formatted it into 4 partitions, one large one for /home (not quite sure what I'm going to do with it yet, but anyway...) and 3 smaller ones which I've mounted as /tmp, /var/log, and /var/cache/apt. (I'm using the Ubuntu it came with.)

I renamed and/or copied the contents of those three directories into the new locations and rebooted and all is working fine. Definitely using less memory now (mainly due to /var/cache/apt) but too early to say if having /var/log on SD is going to have any performance impact.

I'm not a linux expert, feel free to tell me what I've done is bad/wrong/stupid, but if I get some positive responses I'll post more detail on how to do it.

I wonder how the write speed of the card (advertised as 20MB/s) compares to the flash (and the RAM)?

Thanks,
Virge
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DamonHD
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« Reply #1 on: December 12, 2009, 02:13:21 PM »

Hi

IMHO...

1) /tmp should probably be mounted as tmpfs, thus not touching flash at all.

2) Filesystems should probably be adjusted to line up with underling storage block sizes, have noatime and longer commit (or the equivalents).

3) Logging should be tuned, eg to reduce volume and frequency and syncing.

I noted some of the things I did at:

http://www.earth.org.uk/note-on-SheevaPlug-setup.html#storage

Rgds

Damon

PS. FWIW I have symlinked busy/large parts of /var/log and /usr out to my SD card.
« Last Edit: December 12, 2009, 02:15:17 PM by DamonHD » Logged

7iron
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« Reply #2 on: December 12, 2009, 02:46:46 PM »

http://www.plugcomputer.org/plugwiki/index.php/Reduce_Flash_Writes
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DamonHD
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« Reply #3 on: December 13, 2009, 04:46:44 AM »

It's not clear to me that laptop-mode will actually help reduce flash wear at all as long as there is a reasonable 'commit' value on the file systems for example.

Rgds

Damon
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