[clug] Servers, disks and power-use

David C cottrill.david at gmail.com
Fri Oct 12 19:26:24 MDT 2012

I just finished building possibly the most over engineered NAS the world
has ever seen. Due to a late change in requirements it needed to also run
XBMC, so it moved from FreeBSD ZFS to Xbmcbuntu ext4. No LVM, no partitions.

Getting to the point, it runs without fans with 4 x 750GB 5400rpm 2.5 in
disks. The disks peak at 0.45W power consumption and are nearly silent. By
shifting to otherwise identical 7200rpm disks the power and noise double.
Shifting to the same brands 'green' 7200rpm 3.5in disks requires 8 times
the power.

The cost of the energy required to spin the greater diameter disks far
outstrips the cost of the smaller form factor over 2 years.
In my case I can push 105MB/s through my raid array. Any more than that
would require faster disks and CPUs that beat 1GHz.

Ps: I'm happy to admit that my NAS is not the fastest, but it does show
that modest hardware can be better than adequate if carefully built.
 On 12 Oct 2012 13:04, "steve jenkin" <sjenkin at canb.auug.org.au> wrote:

> After the list question on RAID, I wondered what the current
> best-practice is with low- and mid-sized storage on servers.
> I'm thinking that 2.5" drives offer the best Watts/Gb [by a factor of
> 2?], so everything runs cooler and cheaper.
> Do I have the ratio wrong? [3.5" run 3-4 platters vs 1-2 on 2.5"]
> If you pay the extra and get same performance 2.5" drives, it comes down
> to the power/Gb.
> Some time ago on the list, someone commented that HP had only been
> shipping 2.5" drives within server chassis for some time. But I might be
> imaging that.
> For large-sized storage, I think 3.5" will be the leader for a long time
> to come.
> Comments & Corrections, anyone?
> --
> Steve Jenkin, Info Tech, Systems and Design Specialist.
> 0412 786 915 (+61 412 786 915)
> PO Box 48, Kippax ACT 2615, AUSTRALIA
> sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin
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