Does a different hard drive boost a netbook's battery life?

Since it already has an 80Gb hard drive, increasing the storage capacity of the MSI Wind probably isn’t the top priority for most owners. Still, given its two hour (give or take) battery live, we were curious to see how a different hard drive would affect how long this netbook – or any netbook, for that matter – can last away from mains power.

The stock 2.5in Western Digital Scorpio ( WD800BEVS) isn’t anything special – it’s a 5400rpm SATA drive with an 8Mb buffer, a read seek time of 12ms and a peak transfer speed of 1.5Gb/sec (WD’s own figures). So, we wondered how the MSI Wind – or rather the identical, but cheaper and therefore much more appealing Advent 4211 – would fare with a couple of different storage options. Full details after the cut.

The most obvious hard disk upgrade is something bigger, but is something faster also recommended? The faster a hard drive spins, the more power it consumes, but we’ve read anecdotal reports of how the faster data transfer speed of a 7200rpm drive can actually reduce power consumption, since the drive doesn’t need to spin as long as a 5200rpm drive. This sounds like snake oil to us, but we thought we’d try it anyway.

Seagate reckons that its Momentous 7200.3 range of drives has the lowest power consumption of any 7200rpm drive, thanks to a combination of power management improvements and reduced power consumption during idle times. So, we decided to try a Seagate 320Gb ST9320421AS drive in the MSI Wind/Advent 4211.

We were also curious to see if a faster drive would also improve the performance of the MSI Wind. The Intel Atom N270 1.6GHz processor is no powerhouse, even with Hyper-Threading support, so it’s unlikely that the stock Western Digital Scorpio drive acts as any kind of performance bottleneck. Even so, the Seagate ST9320421AS’s 16Mb buffer is twice that of the Scorpio, as is the 3Gb/s SATA interface – though we doubt raw data throughput is a limiting factor for the Atom chip.

Of course hard disks are now completely obsolete 20th century technology, and solid-state drives are now considered cutting-edge for laptops. The complete lack of moving parts means that an SSD uses less power than a hard drive, since there are no platters to spin up – and keep spinning. And with no read/write heads skipping across a fragile magnetic surface spinning at 54mph a few nanometres beneath them, SSDs are also far better suited to life in a laptop that’s likely to get shaken around.

Unfortunately, there is a considerable downside to solid-state drives – the price. We used a Samsung MCCOE64G5MPP 64Gb SSD in our little experiment, but at around £500, few people would actually consider buying one for a standard laptop, let alone a low-cost netbook like the MSI Wind.

Looking at the manufacturers’ figures for power consumption of the three drives, it looks like there should be little difference in battery life between the stock WD Scorpio drive and the Seagate Momentous. The Momentous actually has lower power requirements than the Scorpio, but 7200rpm drives tend to run hotter than 5400rpm ones, which means the Wind might be working harder at keeping everything cool – which of course means increased power consumption.

The Samsung SSD, on the other hand, uses a fraction of the power when reading and writing, and generates almost no heat at all. Which should make things interesting…

Before running our battery life tests, we performed a series of performance tests to see how each drive fared in the MSI Wind. We measured sustained read speed for two sets of increasingly large files – one set of ‘small’ files and one of ‘large’. We also measured the random access seek time, since manufacturer-quoted figures are often somewhat optimistic.

As you can see from the graphs, the Seagate Momentous is twice as fast as delivering data as the WD Scorpio drive, and the Samsung SSD is around 2.5 times faster. There isn’t much different in seek times between the two hard drives – 17ms for the Scorpio; 15.9ms for the Momentous – but the Samsung SSD’s seek time is near-non-existent, at just 0.2ms.

Despite these dramatic speed increases over the stock Western Digital drive though, neither the Momentous nor Samsung SSD made much difference to the MSI Wind’s overall performance. In fact the two upgrade drives only resulted in a 1% increase in overall performance in our benchmarks, and just 2% in multiple application performance. In other words, it seems that the Intel Atom N270’s performance simply isn’t constrained by the storage device and the stock WD Scorpio drive is more than sufficient to handle the processor’s read/write requests.

As it turns out, it’s a similar story with battery life. We ran two sets of tests using Battery Eater – heavy use and light use. In one set of tests with left the MSI Wind in normal mode, with the processor running at its standard 1.6GHz and screen brightness at 50%; in the other we used power-saving mode, which locks the processor at 800MHz and drops screen brightness to 10%. Wi-Fi was disabled in all cases.

We also set the hard drive to spin down after three minutes of inactivity. We usually disable spin-down in our battery life tests, but since Seagate highlights reduced idle-mode power consumption for its Momentous drives, we decided to run our tests twice, once with spin-down disabled and once with it set to three minutes.

We weren’t really that surprised to discover that the marginally more frugal Seagate Momentous didn’t extend the MSI Wind’s life away from the mains, but it’s interesting to note that nor did the 320Gb, 7200rpm Momentous adversely affect battery life, either – it’s essentially the same as with the 80Gb, 5400rpm WD Scorpio.

We were rather more surprised to see that the power-sipping Samsung SSD made almost no positive impact on battery life, though. It added just a few minutes to the heavy and light use scores with the MSI Wind running in normal mode (well within the error margin for the tests), and 20 minutes or so in power-saving mode.

So, it looks like an SSD is complete overkill for a netbook, although it does shave 20g off the weight… You can’t expect to boost battery life with another hard drive either, but it is reassuring to know that a bigger hard drive won’t adversely affect battery life on the MSI Wind (or any other netbook) – at least if you stick with one of Seagate’s Momentous 7200.3 drives.