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Date:      Tue, 21 Jul 2009 16:19:43 +0200
From:      Arnaud Houdelette <arnaud.houdelette@tzim.net>
To:        Mark Stapper <stark@mapper.nl>
Cc:        stable@freebsd.org
Subject:   Re: ZFS RAIDZ and atacontrol spindown settings
Message-ID:  <4A65CE7F.8040906@tzim.net>
In-Reply-To: <4A658205.5000709@mapper.nl>
References:  <4A643F5B.8080806@mapper.nl> <h421n2$1kt$1@ger.gmane.org>	<4A656076.2060205@mapper.nl>	<9bbcef730907210137udf7f90ax21aa530ab859f8a6@mail.gmail.com> <4A658205.5000709@mapper.nl>

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Mark Stapper a écrit :
> Ivan Voras wrote:
>   
>> 2009/7/21 Mark Stapper <stark@mapper.nl>:
>>   
>>     
>>> Ivan Voras wrote:
>>>     
>>>       
>>>> Mark Stapper wrote:
>>>>       
>>>>         
>>>>> Good day,
>>>>>
>>>>> I am the proud user of a FreeBSD 7.2 AMD64 system housing, amongst other
>>>>> things, a data server.
>>>>> My "server"(It's called "Yoshi") runs FreeBSD from a mirrored system
>>>>> disc, and has a zfs RAIDZ array with 4 discs for bulky data.
>>>>> As it is a home server, and I work during the day, these four discs were
>>>>> spinning happily all day long without much use for them doing so.
>>>>> To save the world(and money) I issued the command "atacontrol spindown
>>>>> 1800" for all the discs in my array spinning them down after thirty
>>>>> minutes of idle spinning.
>>>>> So far so good, me very happy! However, when I access the array after
>>>>> the discs have been spun down, it spins up the discs one after the
>>>>> other...
>>>>> Mind you one AFTER the other, taking 4*9 seconds to do a "ls" command on
>>>>> my music directory.
>>>>> Content as I am with the smooth down- and upspinning of the disks, I
>>>>> would like it better if the four discs would spin up simultaneously.
>>>>> Thus my  question: "Is it possible to \"group\" discs to be spun up
>>>>> together, or to issue a custom command upon upspinning of a disc such as
>>>>> to spin up other disks?"
>>>>>         
>>>>>           
>>>> Good question but the answer is probably no - it really only depends
>>>> on how ZFS accesses the drives; if it accesses them in sequence, you
>>>> can't change it.
>>>>       
>>>>         
>>> I've been looking at writing a shell script which monitors
>>> /var/log/messages.
>>> something like:
>>>
>>> If last line in /var/log/messages is like "request while spun down.
>>> Starting."
>>>    spinup disks
>>>
>>> couple of problems though, I should probably poll the kernel messages
>>> every second or so, but if I only check the last linee, I could miss the
>>> spinup message.
>>> I could count the number of lines in /var/log/messages and keep count of
>>> the number of lines i've seen. Problem with this approach is that it's
>>> not very efficient.
>>> So I was hoping there is a way to receive this kernel message directly.
>>> I am now thinking in the lines of a program which received a signal on
>>> new kernel messages available or something similar.
>>>
>>> Any thoughts?
>>>     
>>>       
>> You could do what "tail -f" does and simply hook a kqueue to get new
>> messages from the /var/log/messages file.
>>   
>>     
> I'll try that! thanks!
>
>   
As I get quite the same issue with a 4 disk raidz pool, could you please 
tell me the result of your tries ? which command do you use to force the 
disks to spin up ?

Thanks



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