OK you lucky people, sometimes I think we make this too easy for you! It's time for another superb NightWatchman Server Edition (NWSE) Whitepaper from Mark Blackburn.
I've had the pleasure of knowing Mark since our pre-1E days at Microsoft, and I have to say that during that time I don't think I've come across anyone who is better at conveying complex knowledge in an enjoyable, readable form.
This paper was actually released just before Christmas 2009, and I thought that it was too good to be lost in the haze of good food, snow, and deluges of emails from Amazon telling us all exactly what we should be buying for our loved ones..
Mark’s masterpiece describes perfectly one of the keystones of NightWatchman Server Edition (NWSE) – Drowsy state.
As Marks states in the opening pages of the paper, the very definition of Drowsy is as follows:
drow⋅sy[drou-zee]
–adjective,
1. half-asleep; sleepy.
2. marked by or resulting from sleepiness.
3. dull; sluggish.
4. inducing lethargy or sleepiness.
Synopsis – from the document.
'A server’s main purpose is obviously to serve and therefore, since the server’s workload will be generated by external requests which can arrive at any time, most servers cannot be power managed in the same way as desktop computers (i.e. by turning them off or putting them to sleep). Any power saving mode utilized by a server must therefore always allow the server to service requests (i.e. there shall be no loss of service). It must also not impact the day-to-day operation of the server, so that when the server is performing its main function it should run as quickly as is necessary to provide required response times. If NightWatchman Server Edition detects that there is no useful work being performed for a period of time (by default 30 minutes), then the system can be safely placed into a Drowsy state.'
He goes on to explain just how and when the Drowsy state can and should be used, along with real examples and illustrations – just in case you still don’t get it!It’s a perfect read, along with his previous paper on Useful Work (which you should really read first), so I suggest you download it, grab a coffee and prepare to be enlightened.
Downloads:
Drowsy - The 8th Dwarf
Useful Work Whitepaper
Read the complete post at http://www.1e.com/bizblog/post/2010/01/28/NightWatchman-Server-Edition-Drowsy-State-Explained.aspx