Disk I/O as a bottleneck?

[guy keren]

On Sun, 2011-05-08 at 09:30 +0300, Yedidyah Bar-David wrote:
> On Sun, May 08, 2011 at 07:28:49AM +0300, Nadav Har'El wrote:
> > On Sat, May 07, 2011, guy keren wrote about "Re: Disk I/O as a bottleneck?":
> > > and if you have a lot of money to spend - you could consider buying an
> > > enterprise-grade SSD (e.g. from fusion I/O or from OCZ - although for
> > > your use-case, some of the cheaper SSDs will do) and use it instead of
> > > the hard disks. they only cost thousands of dollars for a 600GB SSD ;)
> > 
> > Instead of buying a huge SSD for "thousands of dollars" another option you
> > might consider is to buy a relatively small SSD with just enough space to
> > hold your "/" partition and swap space. Even 20 G may be enough.
> > The rest of your disk - holding your source code, photos, songs, movies,
> > or whatever you typically fill a terabyte with, will be a normal, cheap,
> > hard disk.
> > 
> > Several of my friends have gone with such a setup on their latest computer,
> > and they are very pleased.
> 
> I am considering, for my next laptop, and taking into account the fact
> that most laptops do not have space for two disks but do have some kind
> of flash memory slot ("card reader") - usually SD-something, to have the
> OS on a (e.g.) SD card of 16 or 32 GB. I have no other experience with
> such cards, so I do not know if they are considered durable enough, fast
> enough - both random and sequential IO, both compared to SATA mechanical
> disks and to SATA flash ones, etc. Comments are welcome :-)

SD cards are much much much slower then SSDs with regards to sequential
I/O - and i think they live a shorter life. if you want to use one - you
should make sure it's set in a mostly read-only setup. problematic
directories include /var and /tmp.

specifically, installing RPMs on such drives works much slower then on
hard disks.

they are still used on various appliances and embedded systems, in such
a "mostly read-only" configuration.


--guy