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neilruston
Posts:155
 | | 07/16/2008 5:30 PM |
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Are you baiting me Neil?
*** Would I do that? :-)
"your method tends towards (mathematically) the random method "
Only if the number of devices approaches infinity... 
*** That's what 'tends towards...' means in the parlance of maths :-)
________________________________
From: ActiveDir-owner@mail.activedir.org
[mailto:ActiveDir-owner@mail.activedir.org] On Behalf Of
neil.ruston@barclayswealth.com
Sent: Wednesday, May 14, 2008 11:15 AM
To: ActiveDir@mail.activedir.org
Subject: RE: [ActiveDir] [OT] Scheduled task on virtual servers
I suspect that as the number of devices grows, your method tends towards
(mathematically) the random method :-)
Random is scalable and as the number of devices/jobs increase, so your
notion of hot spots becomes unlikely too.
Your description of the word 'random' sounds like a description for
'chaos' - they are very different :-)
neil
________________________________
From: ActiveDir-owner@mail.activedir.org
[mailto:ActiveDir-owner@mail.activedir.org] On Behalf Of joe
Sent: 13 May 2008 17:46
To: ActiveDir@mail.activedir.org
Subject: RE: [ActiveDir] [OT] Scheduled task on virtual servers
Added [OT] to subject because this has nothing to do with AD...
You don't want random... You want balanced/scheduled.
Random means any time which could theoretically mean everthing happens
at the same time... you don't specify when with random and all at the
same time is a realistic "when" that could occur or more likely you will
get "hot spots" where the randomess algorithm isn't working properly.
You want to figure out some scheme for load balancing across that period
of time. It could be as simple as having a schedule and saying X events
can occur in any given period and then hand out the periods to the
servers where they are available.... Say break up your 12 hour period
into what.. 30 minute slots maybe? And then hand out those every other
slot until they are all used and then go back and hand out the other
slots and then when you get through all of that hand out slots that have
the fewest schedules jobs in the slot.
If you want to get really fancy you can block the period up into say 10
minute slots and then assign duration values to each the jobs that need
to be scheduled and have them take up the appropriate slots. You could
also assign "weights" to the scheduled jobs for things like
CPU/Disk/Network so you can factor in overall hit to the physical server
for CPU or Disk or Network and then avoid scheduling high CPU items
together or high disk items together.
You can be as simple or complex as you want, but I wouldn't use a
randomization algorithm. You want more control than that and can do
better scheduling than random.
joe
--
O'Reilly Active Directory Third Edition -
http://www.joeware.net/win/ad3e.htm
________________________________
From: ActiveDir-owner@mail.activedir.org
[mailto:ActiveDir-owner@mail.activedir.org] On Behalf Of Figueroa,
Johnny
Sent: Tuesday, May 13, 2008 11:21 AM
To: ActiveDir@mail.activedir.org
Subject: [ActiveDir] Scheduled task on virtual servers
Good morning experts, we have an interesting thing going on. Something
that I have not seen talked about when it comes to virtualizing servers.
Whenever you have hundreds of virtual servers doing something to their
"local" C drives at the same time, that is a problem.
So you P2V the physical server which has a few scheduled tasks: System
State daily, weekly and monthly backups; Registry backups. All writing
to the local C drive. When hundreds of physical servers do this to their
local drives it is not a problem. When you have this happening on
hundreds virtual servers with shared storage for their C drives, that
can drive IO very high on the backend disk arrays. We ran into the same
thing with the daily antivirus definitions from McAfee which come down
every day around the same time. We solved that problem by randomizing
the tasks to get the new DATs.
We create the scheduled system state backups and the registry backups
with a VB script when we build the servers. I am trying to figure out a
way to randomize these tasks across the virtual servers. Say, given a
time window...say 6PM to 6AM. I am not very good at this kind of thing.
Not sure if you just randomize or do I need to use some virtual server
input file or database... worst yet, I can't get my head around the code
to randomize period.
Any input would be appreciated.
Thanks
Johnny Figueroa
Systems Engineer Senior Consultant
Information Technology
Banner Health
602 747 4195
Johnny.Figueroa@bannerhealth.com <mailto:mike.garner@bannerhealth.com>
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