G-Technology G-DRIVE Slim 320GB Review

Since I use an 11.6 inch MacBook Air as my normal working computer and it currently has a 64GB SSD, I have been on the lookout for compact external storage. The MacBook Air only provides USB 2.0 as an interface for that external storage unless you count the SDHC slot but that is only available on the 13.3 inch MacBook Air. In any case, adding up to a 32GB SDHC card would not be enough.

A Few Options

To this end I started searching for a compact USB 2.0 hard drive. Initially I used an older LaCie Data Bank 60GB 1.8 inch external hard drive. This was a nice drive but once again 60GB is not enough for external storage and the drive offered a slow 21MB/s transfer speed. I have also used older Western Digital My Passport drives but the newer drives have micro USB connectors which can be very flimsy and just are not to my liking. Toshiba and Seagate also make a number of external 2.5 inch drives but nothing jumped out at me. I wanted something smaller which caused me to keep looking.


Shortly after the 2010 MacBook Air models were released, G-Technology (by Hitachi GST) announced a new external USB 2.0 hard drive specifically designed for the MacBook Air. This new drive was called the G-DRIVE Slim and comes in a 320GB size. While 500GB or maybe even 750GB might be nice, 320GB is ample and will work well to store extra downloads, my mobile iTunes library, and whatever else does not fit on the internal 64GB SSD. The best part about this drive is its size. The G-DRIVE Slim is only 9.9mm thick which seems impossible given normal drive sizes.

Z-series 2.5 inch Hard Drives

Most normal 2.5 inch laptop hard drives are 9.5mm high and can be single or dual platter designs. Some unusual drives can be 12.5mm such as the current 1TB 2.5 inch drives due to having three platters. The 9.5mm z-height, as it is called, is an obvious design limitation for the thickness of external drives. Hitachi GST turned the z-height issue on its head by introducing 2.5 inch drives with a 7mm z-height which is only achievable by using a single platter.

The initial Hitachi Z-series drives were announced in June 2010 and featured up to 320GB of storage in a single platter design. The Travelstar Z5K320 drive in the 320GB size is what the G-DRIVE Slim 320GB is built around. This past December, Hitachi GST also announced a new Z5K500 series of drives which feature sizes up to 500GB in the same 7mm z-height. In the same press release, a G-DRIVE Slim 500GB model was announced for Q1 2011 but has yet to appear on the market.


The G-DRIVE Slim 320GB is an amazing 5.063″ by 3.23″ by 0.39″ size. This is the most compact 2.5 inch drive I have ever used and is a pleasure to use.


Unlike the LaCie Data Bank I mentioned earlier, the Z5K320 drive in the G-DRIVE Slim 320GB is fully capable of excellent performance and the limiting factor for performance is the USB 2.0 interface. In testing using digilloyd DiskTester, the G-DRIVE Slim 320GB is able to achieve essentially the maximum performance that the USB 2.0 interface can provide. The sustained write speeds ran between 34.0MB/s and 36.6MB/s and the sustained read speeds ran between 38.5MB/s and 40.2MB/s


I can fully recommend the superb G-DRIVE Slim 320GB as the very best compact hard drive especially well matched to the MacBook Air. Its size, performance, and aesthetic appeal are all fantastic. G-Technology has done a superb job with this product. I am looking forward to upgrading from the G-DRIVE Slim 320GB to the 500GB model once it is available.

Purchase the G-DRIVE Slim

The G-DRIVE Slim 320GB is available from Amazon.com for around $90 with free shipping and no sales tax.