[Tinyos-Storage WG] Meeting minutes 05/04

[Gaurav Mathur]

05/04

* Working group policies
** For joining significant experience building a storage system is
required, and joining 4-6 consecutive meetings
** If member misses 4-6 consecutive meetings, they are pinged to see if
they want to continue.

* For NAND flash, writing data sequentially within an erase block
** NOR flash states that over-writes should not be done, but in practice
this works
** Not sure if this is a hard/soft constraint for NAND flashes.
** Should not enforce the softer constraints – user should be aware of
the quirks. Best practice and core implementations _should_ not use any
of the quirks
** Is this a performance constraint or a data reliability constraint ?
** How should this be exposed to the application ?

* JEDEC
** Should FlashSettings interface query the flash dynamically ?
** Probably more useful for MMC/SD cards since they can be swapped at
run-time

* Multiple sector sizes
** Example: If flash supports 1 and 4 pages as erase units, then as an
optimization a 4 page volume could use a single 4 page erase operation
to erase the volume at one shot.
** Should the Flashsettings interface expose multiple flash sector sizes ?
** If so, how ?

* Add Best/Worst Practices section to TEPS
** sequential vs non-sequential writes
** overwrites to same location on NOR/NAND flash
** Number of writes to a page

* Plan for next week
** Add capsule objects to TEP 129
** Prabal to take a crack at TEP 128
** Checkpointing and Rollback support should be in a separate TEP
** Take a look at the hardness/softness of the different constraints
discussed

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