second HDD, ssd, and battery life

Hello,
I am almost sure of the laptop I will buy (Precision M4600), but some last details need to be cleared out.
One of these details is the HDD configuration. I have to choose between one single 500GB 7200rpm, one single SSD sata III 128Gb, or two drives, combining both of these drives.
The prices is not very expensive, the upgrade between single HDD/single SSD is only 140€, and the secondary HDD is then obtained for around 80€ (all including tax). All these components then benefit from the 5 year business warranty the laptop has + up to date firmware etc, so no pain with configuration, or trouble to open the laptop and then messing with painted screws that I am always afraid will void out my warranty (the M4600 has a pretty difficult access to the hard disks, I've seen)
My question, to which I have found no answer so far, is the impact on the battery of such a choice. First, what is the difference between average 7200rpm HDD/ sata 3 ssd, in terms of energy consumption? And then, what does a secondary HDD, with secondary controller etc, add to that energy consumption?
And if this consumption is high, is there a way, in win7 for example, to disable the secondary hard drive, without resorting to overall power saving mode? (I mean, a command that will do nothing but switch off the secondary hard drive)
Ans apart from the absolute consumption of the drives itself, will it be nothing in comparison to that of the M4600 platform, its quad core, WUXGA display and 2 fans?

I know there is a huge sub-forum about ssds but as here my main concern is the battery, I posted it here...

Thanks for your help!

 

I wouldn't worry about this for more than a couple of seconds.

Any combination of single HDD's (5400 RPM's vs. 7200 RPM models) have always been within the margin of error in battery life (10 min?). Same goes with most SSD's - with the notable exception being the Intel 320 Series 160GB model as setup in my U30Jc.

See:
http://forum.notebookreview.com/7766632-post2079.html


No such way to disable a second HDD and SATA controller - because it is simply not needed.

Also, with a two drive setup - depending on how you actually setup the system (the Dell default 2 drive configuration would last about 12 seconds in my hands) you may get even more (a couple of minutes?) battery life as each storage device is used in a far less stressful role (if we move the Users folder to the mechanical drive, for example, and each drive is either simply reading or writing, but not both simutaneously).

If your concern is for the battery - then I would recommend to buy two - use one until it is at around 20-40 percent charge and switch to the other to finish off your day (where you would then fully charge (within a couple of hours) the depleted one in the system and remove and fully charge the other one afterwards and repeat the above process).

This will give you the most run time on battery power while also being as gentle as possible to your batteries for the longest service time.

Good luck.

 

I wouldn't worry about battery drain.

A typical mechanical HDD drains about 1.0W (idle) - 3.0W (load).
A typical SSD will drain about 0.5W (idle) - 2.5W (load).

Considering that a secondary mechanical HDD will be idle 98% of the time (since the SSD will handle the OS + apps + games), then you can consider an extra mechanical HDD to add 1.0W battery drain.

A review I read of the Dell Precision M4600 gets about 5 hours of battery life in web browsing mode on the 9-cell battery (97Wh). That puts the battery drain of the Dell Precision M4600 at about 20W/h. A secondary mechanical HDD would drain an additional 5% battery life, which means a 5-hour runtime goes down to 4h45m. I would consider that to be within a margin of error.

If you really want to save battery life, get a 5400rpm hard drive instead as your secondary hard drive. In an SSD + HDD dual-drive configuration, the HDD is used for bulk storage of content (documents, videos, music, etc). And in those cases, the faster read speeds of a 7200pm drive will be irrelevant. So you might as well go with a cheaper, slower, cooler, and lower power 5400rpm drive.

 

Hello,
thanks a lot for your detailed replies, it is precisely what I needed (quantified consumption etc). Then I guess I will go for the 2-drive config.
2 comments: to kent1146, there is no 5400rpm option, at least on the shopping page on which I find my prices, I think Dell gave it up on its higher-end models now.
And the other one, for tilleroftheearth:
what do you mean by "the Dell default 2 drive configuration would last about 12 seconds in my hands"? Why is their original configuration so bad?
Thanks again!

 

What I meant was that Windows will be installed on only one drive (SSD or HDD) and the secondary HDD will be simply extra storage. Not to mention all the junk that will undoubtedly be installed for 'free'.

What I would do is clean Win7x64 install and move the Users folder to the secondary HDD to optimally use both drives for the fastest overall (sustained) experience possible.

See:
http://forum.notebookreview.com/win...gramdata-folder-separate-drive-partition.html


In addition to simply locating the Users folder to another physical drive, I would also short stroke both the SSD (or main O/S HDD) and the partition of the secondary drive where 'Users' will be located.

By using less than the full capacity of an SSD you gain a lot of leeway in how hard you can hammer it and still have a long life expectancy from the drive (by decreasing WA (write amplification) and increasing the efficiency of how the TRIM and GC works in the drive).

With a HDD the benefits of 'short-stroking' include a fast and responsive system - not to mention an 'average' transfer rate that barely falls below the maximum the drive is capable of.

Combine the above with two SATA ports for Windows to use the drives as it wishes (and needs to...) and the whole is better than the sum of the parts.

On a notebook, this setup is easily noticeable - on a high-end desktop platform, this type of setup makes the system fly with nothing seemingly able to slow it down.

It may take some time to get this kind of 'optimum' 2 drive configuration working properly - but the time investment is worth every second spent. You'll get it back many times over each time you use your optimized system until you sell/tradeup to something better (and you do this process again).

Good luck.