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From: "Mathias Burén" <mathias.buren@gmail.com>
To: Roberto Spadim <roberto@spadim.com.br>
Cc: Piergiorgio Sartor <piergiorgio.sartor@nexgo.de>,
	linux-raid@vger.kernel.org
Subject: Re: RAID HDDs spin up sequence
Date: Mon, 31 Jan 2011 21:11:21 +0000	[thread overview]
Message-ID: <AANLkTi=Q7E5xhOxXA5KusWgpSb97hnmnbcm0fD1C9N5w@mail.gmail.com> (raw)
In-Reply-To: <AANLkTinPTaDfVtjMfz7DHUa95cKFF7MZeg=WhuuTnZM8@mail.gmail.com>

On 31 January 2011 21:09, Roberto Spadim <roberto@spadim.com.br> wrote:
> 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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I would guess, that on a RAID0 setup, any read to that md device would
wake every disk up in that setup. No?

// Mathias
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  parent reply	other threads:[~2011-01-31 21:11 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
2011-01-31 21:11   ` Mathias Burén [this message]
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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