Re: [tlug] Making better use of SSDs?

[Nava Whiteford <new@example.com>]

> > > Actually, there is an effort going on to use SSD for hierarchical
> > > storage. Ie use the SSD to cache reads and writes from a normal
> > > harddisk.
> > > 
> > > I don't remember where i read about it, it was most likely lwn.
> > 
> > That's bcache. [..]
> 
> There are bcache and flashcache for this.
> Looks like bcache is used/pushed by google, flashcache by facebook.  
> Both seem to be usable, but have not made it into the kernel.

As an aside, I've recently been using an SSD as swap to see if I can avoid
buying the large memory server I was asking about.

As expected, it sucked pretty badly. The system has 56Gb of RAM, the process
is single  threaded and compute bound, and should have a random access pattern.

>From 56Gb to 70Gb, I get about 70% CPU usage. Beyond that things get steadily 
worse, finally dropping to 10%.

I've also tried using zram, for in memory compressed swap. Currently this seems even worse.

Nav