From: Roberto Spadim <roberto@spadim.com.br>
To: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>
Cc: linux-raid@vger.kernel.org
Subject: Re: RAID HDDs spin up sequence
Date: Mon, 31 Jan 2011 19:10:17 -0200 [thread overview]
Message-ID: <AANLkTimSj9P7QBgt6uJ7DPEKyMdqBYVEP_CweZdHj6jV@mail.gmail.com> (raw)
In-Reply-To: <AANLkTinPTaDfVtjMfz7DHUa95cKFF7MZeg=WhuuTnZM8@mail.gmail.com>
normaly...
raid1 send many writes and one read
raid0 send one write and one read
2011/1/31 Roberto Spadim <roberto@spadim.com.br>:
> you psu must be dimensioned to work with everythink at full work load
> (it´s a real production NAS right?! not a test)
> your SAS/IDE/SATA controller and HDD manual should be checked
> how hdd wake up? one command (read/write) over sata/sas/ide channel wake it up?
> on linux raid we have a read algorithm and a write algorithm
> if a raid1 write occur all disks will wake up
> if a raid1 (raid0 or another) read occur only the disk will wake up
>
> but check you SATA/IDE/SATA controller, how it wake up your disk, and
> how you hdd wake up
>
> 2011/1/31 Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>:
>> Hi all,
>>
>> assuming there is a NAS, with, for example, 10 HDDs
>> in RAID-6. Assuming the HDDs are put in standby, in
>> order to save energy, when the NAS is not used.
>> How is the spin up sequence when the corresponding
>> /dev/mdX device is accessed?
>> Will the system spin up one HDD at time or all together?
>>
>> Obviously, one at time will limit the peak current,
>> thus allowing a better dimensioned PSU, working almost
>> always around the optimal efficiency point.
>>
>> Thanks a lot for any information on the topic,
>>
>> bye,
>>
>> --
>>
>> piergiorgio
>> --
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>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>
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Roberto Spadim
Spadim Technology / SPAEmpresarial
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next prev parent reply other threads:[~2011-01-31 21:10 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-31 20:18 RAID HDDs spin up sequence Piergiorgio Sartor
2011-01-31 21:09 ` Roberto Spadim
2011-01-31 21:10 ` Roberto Spadim [this message]
2011-01-31 21:11 ` Mathias Burén
2011-01-31 21:25 ` Roberto Spadim
2011-01-31 21:29 ` Mathias Burén
2011-01-31 21:35 ` Roberto Spadim
2011-01-31 22:23 ` Piergiorgio Sartor
2011-01-31 22:42 ` Roberto Spadim
2011-01-31 22:42 ` Roberto Spadim
2011-01-31 23:07 ` Piergiorgio Sartor
2011-01-31 23:12 ` Roberto Spadim
2011-02-01 1:45 ` Phillip Susi
2011-02-01 12:39 ` Roman Mamedov
2011-02-01 13:10 ` John Robinson
2011-02-01 21:37 ` Stan Hoeppner
2011-02-01 22:46 ` Roberto Spadim
2011-02-01 13:55 ` brian.foster
2011-02-01 14:37 ` Roberto Spadim
2011-02-01 14:44 ` Roberto Spadim
2011-02-01 15:01 ` John Robinson
2011-02-01 15:46 ` Roberto Spadim
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