Re: MDADM RAID1 of external USB 3.0 Drives
On Sun, Sep 21, 2014 at 03:51:54AM +0200, lee wrote:
> Andrew McGlashan <andrew.mcglashan@affinityvision.com.au> writes:
>
> > Whilst it is usually quite easy to find older server class hardware at
> > bargain prices (compared to new), it is often the case that older
> > hardware is slower and much less power efficient to newer hardware and
> > the pricing on lots of new gear has collapsed enough to make buying new
> > a much better option in many cases.
>
> Hm, would you have an example for this? As far as I have seen, the
> difference in price is somewhere around EUR 6000 when you're looking at
> 19" servers. The difference in power efficiency is about 59W (at best)
> vs. 180W at idle. IIRC, the HP Microserver is rated at 30W.
>
That depends very much on what you want to do / how much you need.
Take a fairly common example of the sort of thing you have in a data centre.
An IBM 3550 1U server. They're up to about the fourth generation in the same series.
So you go from 2 Intel Xeons five years ago, with 73G SCSI disks and an old RAID controlller
to 2 x Intel Xeons today with 2 x 300G disk and a newer RAID controller - but faster disks,
higher capacity, probably Hyperthreading/2 more cores, significantly faster memory bandwidth - and probably the option of better
than 1G Ethernet connectivity for a similar sort of price point.
Pick up the oldest version of the IBM 3550 and you might be talking a 15W power difference
and 20 - 30% slower than the newer kit for some tasks and the memory may not be straightforward
to find. [Nor is the newest - and in both cases, you'll probably have to buy IBM branded parts]
If you recycle your hardware on a three year cycle / rent on a three year contract, that's the sort of
improvement you'll see as the generations change. If you're at home and "just want a server" then it
probably doesn't make too much of a difference. If you're running racks full of kit, ti starts to matter,
not least because you have to keep spares around for different generations.
Likewise, the four year old desktop machine I've given away was £699 when bought by my father and is worth nothing now.
For £150, I can now buy a faster better desktop machine than I can build, given that my time probably costs > £20
an hour and I have all the problems of matching components etc.
I can buy a last generation HP microserver with
4GB of memory for £149 brand new or the latest greatest for about £800 fully kitted out, run it for three years
and write it off.
My daughter's machine was one of the £150 quad core machines. Add a graphics card for £50, an SSD for £100 and
it's close to the spec of the £800 "top end family desktop" machines.
Two years on, and the base machine is now an 8 core, with double the basic hard disk at the same power consumption ...
> How many years does it take before the power savings pay out (for a
> server you're running at home where you don't have AC and where the
> generated heat contributes to heating in the winter)? To some extend,
> you also need to consider parts: like what does it cost to upgrade the
> memory or to replace a RAID controller or a fan.
>
> I'm neglecting that newer hardware is likely to be faster because the
> old server hardware I have shows stunning performance. --- Hm, actually,
> I don't have any new hardware at all because even for my desktop, I'd
> have to put out a huge amount of money to get anything significantly
> faster than what I currently have. The newer, faster hardware would
> require more power, not less, so I'd also need a second UPS, or a bigger
> one. And I don't even mention the hassle of UEFI ...
>
> Of course, don't buy too old, that's not worthwhile for many reasons.
>
Unless you go round picking up non-working machines / old machines for nothing
and use them as spare machines to play around with. See above - a four year old
desktop machine costs nothing
Hope this helps,
All the best,
AndyC
>
> --
> Knowledge is volatile and fluid. Software is power.
>
>
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