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Re: apt-get update: unnecessary use of disk space

Andrei POPESCU wrote:
> Bob Proulx wrote:
> > Of course now with SSDs that standard thinking needs to be thought out
> > again.  I haven't seen any benchmark data for full SSDs.  I imagine
> > that it will have much flatter performance curves up to very full on
> > an SSD.  It would super awesome if someone has already done this
> > performance benchmarking and would post a link to it so that we could
> > all learn from it.
> As far as I understand SSDs can drop performance significantly when 
> full, but for entirely different reasons. Probably a good start would be 
> this Wikipedia article:
> https://en.wikipedia.org/wiki/Write_amplification , especially the 
> section on over-provisioning.

Over-provisioning is the reserved space that the vendor keeps to so
that the physical layer of the storage device never actually becomes
very full.  The more the vendor does over-provisioning the less full
the drive can get.  Even if the logical layer appears full.  The drive
needs big blocks of free space in order to be able to operate since it
will erase in large blocks.  And of course that reduces the impact of
not using trim.  This is why I don't think an SSD would degrade in
performance very much at all when the logical layer of the file system
is very full.


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