>>>>> "et" == Erik Trimble <erik.trim...@sun.com> writes:
et> Probably, the smart thing to push for is inclusion of some new
et> command in the ATA standard (in a manner like TRIM). Likely
et> something that would return both native Block and Page sizes
et> upon query.
that would be the *sane* thing to do. The *smart* thing to do would
be write a quick test to determine the apparent page size by
performance-testing write-flush-write-flush-write-flush with various
write sizes and finding the knee that indicates the smallest size at
which read-before-write has stopped. The test could happen in 'zpool
create' and have its result written into the vdev label.
Inventing ATA commands takes too long to propogate through the
technosphere, and the EE's always implement them wrongly: for example,
a device with SDRAM + supercap should probably report 512 byte sectors
because the algorithm for copying from SDRAM to NAND is subject to
change and none of your business, but EE's are not good with language
and will try to apelike match up the paragraph in the spec with the
disorganized thoughts in their head, fit pegs into holes, and will end
up giving you the NAND page size without really understanding why you
wanted it other than that some standard they can't control demands it.
They may not even understand why their devices are faster and
slower---they are probably just hurling shit against an NTFS and
shipping whatever runs some testsuite fastest---so doing the empirical
test is the only way to document what you really care about in a way
that will make it across the language and cultural barriers between
people who argue about javascript vs python and ones that argue about
Agilent vs LeCroy. Within the proprietary wall of these flash
filesystem companies the testsuites are probably worth as much as the
filesystem code, and here without the wall an open-source statistical
test is worth more than a haggled standard.
Remember the ``removeable'' bit in USB sticks and the mess that both
software and hardware made out of it. (hot-swappable SATA drives are
``non-removeable'' and don't need rmformat while USB/firewore do?
yeah, sorry, u fail abstraction. and USB drives have the ``removable
medium'' bit set when the medium and the controller are inseperable,
it's the _controller_ that's removeable? ya sorry u fail reading
English.) If you can get an answer by testing, DO IT, and evolve the
test to match products on the market as necessary. This promises to
be a lot more resilient than the track record with bullshit ATA
commands and will work with old devices too. By the time you iron out
your standard we will be using optonanocyberflash instead: that's what
happened with the removeable bit and r/w optical storage. BTW let me
know when read/write UDF 2.0 on dvd+r is ready---the standard was only
announced twelve years ago, thanks.
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