Ric Wheeler wrote:
After talking to some vendors, one issue that came up is that the arrays
all have a different size that is used internally to track the SCSI
equivalent of TRIM commands (POKE/unmap).
What they would like is for us to coalesce these commands into aligned
multiples of these chunks. If not, the target device will most likely
ignore the bits at the beginning and end (and all small requests).
I have been thinking about whether or not we can (and should) do
anything more than our current best effort to send down large chunks
(note that the "chunk" size can range from reasonable sizes like 8KB or
so up to close to 1MB!).
Note, this is relevant to MMC as well. They have an "erase" command,
which is equivalent to discarding a group of sectors, e.g., 128KiB. So
we would speed MMC up if we could make sure our discard requests are:
1. 128KiB aligned
2. of 128KiB in size
P.S. Gropup size is MMC-specific.
--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)
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