On 17/10/16 11:31, John Rumm wrote:
On 17/10/2016 10:45, The Natural Philosopher wrote:
On 17/10/16 09:37, John Rumm wrote:
In reality it could be anywhere on any boundary the
SSD firmware and processor puts it.

Not quite - there is not a one to one mapping of OS allocation units to
flash pages. For optimum performance you need to ensure that whichever
allocation unit you update, the SSD can do that update by operating on
one (and only one) page of flash. With the wrong alignment, you can end
up with the SSD needing to do two page updates for each OS allocation
unit update.


However all that may be true, but its not under user level control via
partioning, and its handled internally by the SSD.

There is no obvious way

Actually, I can think of several


a SSD could make a sensible choice to internally
remap alignment if it turns out you have managed to install an OS
partition with a start LBA offset from the ideal. Especially as one
physical drive can host more than one partition, and if you really
tried, you could end up with several partitions each with different
alignments.

In logical space. There is no reason for the SSD not to have enough
sense to map some odd 512 byte sector starting point to the start of a
physical page.

Especially if it understands partition information, which is not exactly
rocket science.


It makes far more sense to ensure the partitions are aligned so that the
OS allocation unit is on a 4K boundary (which is the default action on a
modern OS anyway)

My point is that that is what the SSD firmware will in fact do.

No matter where the partition boundary is.








--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

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