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

On Du, 06 iul 14, 23:30:28, Bob Proulx wrote:
> 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.

Well, my point was that the reserved blocks would be useful for SSDs as 
well, even if for entirely different reasons ;)

Kind regards,
Offtopic discussions among Debian users and developers:

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