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Re: Most energy efficient (home) setup
From: PC <paul4004 () gmail com>
Date: Fri, 13 Apr 2012 13:59:52 -0600

It exists.  Google for "unRAID"  It uses something like Raid4 for Parity
data, but stores entire files on single spindles.  It's designed for home
media server type environments.  This way, when you watch a video, only the
drive you are using needs to power up.  It also lets you add/remove
mismatched disks with no rebuild needed.


* Better power management: not all hard drives are required to be spinning
in order to access data normally; hard drives not in use may be spun down.

However modern "green" drives don't take that much power.

On Fri, Apr 13, 2012 at 1:06 PM, Jeroen van Aart <jeroen () mompl net> wrote:

Leo Bicknell wrote:

But what's really missing is storage management.  RAID5 (and similar)
require all drives to be online all the time.  I'd love an intelligent
file system that could spin down drives when not in use, and even for
many workloads spin up only a portion of the drives.  It's easy to
imagine a system with a small SSD and a pair of disks.  Reads spin one
disk.  Writes go to that disk and the SSD until there are enough, which
spins up the second drive and writes them out as a proper mirror.  In a
home file server drive motors, time you have 4-6 drives, eat most of the
power.  CPU's speed step down nicely, drives don't.

Late reply by me, but excellent points.

A combination of mdadm and hdparm on linux should suffice to have a raid
that will spin down the disks when not in use. I have used for years a G4
system with a mdadm raid1 (and a separate boot disk) and hdparm configured
to spin the raid disks down after 10 minutes and it worked great.

I think in a raid10 this would only spin up the disk pair that has the
data you need, but leave the rest asleep. But I didn't try that yet.

What I'd like is to have small disk enclosuer that includes a whole (low
power) computer capable of having linux installed on some flash memory. Say
you have an enclosure with space for 4 2.5 inch disks, install linux, set
it up as a raid10, connect through USB to your computer for back up


Earthquake Magnitude: 3.0
Date: Friday, April 13, 2012 17:45:06 UTC
Location: Central Alaska
Latitude: 64.0464; Longitude: -148.9850
Depth: 1.80 km

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