Regarding temporary "pauses", perhaps due to using an SD card with an XO

Chris Marshall devel.chm.01 at
Sat Oct 13 17:16:39 EDT 2012

I too have observed increasingly often "pauses"
on my XO but have had no idea how or where to
start to debug the problem.

One thought I had is that the swap file on the SD
card is the source of the problem (somehow) but
I still have the pernicious/persistent hanging even
without using the swapfile.

I'll try with a brand new 16GB SD card to see if
that helps.


On 10/13/12, Mikus Grinbergs <mikus at> wrote:
> Lately there has been discussion about using an SD card to expand the
> "storage" capability of the XO.  [For instance, discussion of when an XO
> functions as a server, having it keep its database on an SD card.]
> What I want to mention is that I experience occasional "pauses" on my XO
> systems (each has a "permanent" SD card, on which I keep Activities,
> Linux executables, etc.).  I do not know what causes these "pauses", but
> my best guess is the following (particularly since "pauses" often occur
> during a CLI command that is "massively" accessing the SD card).
> My guess:   SD cards have an "embedded chip" which is responsible for
> "wear levelling" the electronic components used to keep the data.  It
> does this by internally 'rearranging' "which data block is physically
> kept where".  I think this 'rearranging' action by the "embedded chip"
> gets launched (when some 'internal' SD card thresholds are met) during
> an I/O access by the (XO) host -- and this "rearranging" results in that
> host's I/O access being DELAYED until the "embedded chip" is done.
> I have not compared the "performance" (from the user's point of view) of
> running an Activity "from the SD card" vs. running it "from the XO".
> But I do have the impression that the duration of the occasional
> "pauses" which I as a user notice while running "with the SD card" have
> gotten LONGER as my XOs have migrated to using ever-larger SD cards.
> mikus
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