[CentOS] Being Green, Time to make the servers sleep!

John Hinton webmaster at ew3d.com
Thu Mar 19 15:22:27 UTC 2009


Theo Band wrote:
> Hugh E Cruickshank wrote:
>   
>> From: James Bensley Sent: March 19, 2009 04:13
>>   
>>     
>>> I am trying to be green and put our backup servers to sleep during the
>>> day and have them wake on LAN and fire back up at night for our
>>> nightly backups as "sleep" is a sort of low power usage mode.
>>>     
>>>       
>> I can not comment on how to do what your asking but I can see one
>> potential problem. If your solution involves booting the backup server
>> and during the boot an error is detected in the filesystem check the
>> boot process will halt waiting for you to manually correct the problem.
>> Of course you can avoid the problem by making your backup scripts on
>> the primary server can implement a time limit on the wait for the
>> backup server and if the wait times out then skip the backup.
>>
>> Someone out there more knowledgeable then I (and there are many<g>) may
>> be able to suggest a way to alter the boot to avoid the filesystem
>> check (or the halt).
>>   
>>     
> I would not disable the filesystem check at boot. Those checks are
> needed. You can lower the frequency of checking using tune2fs (not
> needed to check after a certain number of boots if you boot daily). I
> think it is good practice to check your backup status on a regular basis
> anyway. You would notice a problem with your backup server in this way.
>   
I never figured out why the manufacturers thought that ATX was better 
than AT when it comes to Green? Yeah, off topic a bit, but an AT machine 
when turned off disconnects the power supply from the current. ATX, just 
powers down the computer, leaving the PS in a lowered power state, but 
apparently this can draw up to 60% of the working power needed. Funny to 
me that at the same time ATX came out, suddenly "Green" started showing 
on the bios screens. Yeah, it sleeps better during the day during 
non-use times until you get tired of waiting for it to wake up and turn 
all of that off, but it doesn't sleep nearly as well at night when 
everyone has quit for the day.... unless you put it on a switchable 
power strip. And I bet most people have no idea about the power 
consumption of an ATX machine and think it's using no power when the 
computer is not running.

Of course, this has nothing to do with full time servers. We are 
wasteful in so many ways. TVs... same deal, just so that when we turn 
them on they start up faster.... and on and on and on it goes. But it is 
good that you are trying to help with your backup server.

It would be interesting to put a wattmeter inline on the power cord to 
see how much current it's drawing running vs. in sleep state. I guess 
with an AT machine, one would have to use one of those old timers that 
switch on a plug.... something else that uses a bit of electricity, but 
I bet less than a power supply in sleep mode. Actually, one of those 
timers might be a good solution for you if you really want to be green.

John Hinton


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