Full Circle Magazine FR

This hard drive is a 2.5” unit for laptops, that, at approximately 8mm in height, should fit most laptops and netbooks. It combines a standard platter 1000 GigaByte hard drive, and an 8 GigaByte Solid State Drive (SSD), both integrated into a hybrid unit that Toshiba calls a Solid State Hybrid Drive (SSHD). The SSD part is a smaller but much faster storage space, and is used as a cache to access data at higher speeds than would normally be possible with a platter drive. The cost is lower than would be possible with a pure SSD drive of similar capacity, though higher than a platter drive. Data management is performed by the hard drive circuitry, with no intervention needed (nor indeed possible) from the operating system. This is a departure from Apple’s Fusion Drive, where the OS itself manages data transfers between the SSD and the platter parts of the drive. I tested this unit in an Acer Aspire AO-722. This 11.6” netbook has an AMD C-60 64-bit processor, and originally came with a 320 GigaByte platter drive. When upgrading to an SSD drive in search of more speed, the small case dimensions meant that the platter drive had to go to make space for the replacement SSD drive, a Crucial M4. This worked fine, system and application boot times went way down and performance was in line with what could be expected from a lightweight computer with a fast drive: the limiting factor was now the processor, not the hard drive. However, I had achieved this at the expense of losing disk space, since the Crucial unit holds only 64 GB. Other SSD drives were available, but at extra expense. Though their prices have gone down during the last year, users should still expect to pay about $1.00 per GigaByte: large SSDs in excess of 500 Gigabytes may be worth more than the computer itself! If the hybrid drive holds its promises, I may be able to get the best of both technologies within the limited physical space available for this small computer.

I already had a working Xubuntu 14.04 system I was happy with, so I decided to clone the existing setup instead of going through the full installation process. The system detected the new drive - connected through an external USB adapter - as a single unit with no problems. The drive comes completely uninitialized, with no partition table as reported by gparted. My original partitioning consisted of an ext4 boot partition. The rest of the Crucial drive was set up as an LVM physical unit, out of which I had carved a 15 GigaByte logical volume for the system root, and another for /home. There was still some space available for future applications. /dev/sda2 243M 40M 187M 18% /boot /dev/mapper/SSD–VG-System 15G 7,8G 7,1G 49% / /dev/mapper/SSD–VG-Home 20G 5,0G 14G 27% /home After creating an MS-DOS partition table and partitioning the new Toshiba hybrid drive in the same way, I then copied over each partition, installed GRUB on the new unit, and booted the computer from the new drive over USB just to make sure everything was working correctly. I now got up to 901 GigaBytes free for user data - or 850 GB when the standard 5% was reserved for root’s use. /dev/sda1 976M 40M 870M 5% /boot /dev/mapper/SSHD-System 15G 7,8G 7,1G 49% / /dev/mapper/SSHD-Home 901G 5,0G 850G 1% /home

I then switched off the computer and got out the old screwdriver to install the hard drive in its place. The hard drive is at the top left of the picture, with the CPU and its cooling fan visible at the top right, RAM slots at bottom right and the WiFi card at bottom left. As you can see, there is little space left over in this computer! Now, for some testing. I compared several typical actions both with the former Crucial SSD and the new hybrid drive. In both cases, the system comes up in 31s - there are no measurable differences. With the new drive, Gimp starts up in 18s, while LibreOffice Writer needs just 5s. These are just about the same times measured with the SSD, and a definite advance over the traditional spinning disk drive this computer came with. Speeds are much higher and the system is much more responsive. In fact, I did not see any user-noticeable differences between the hybrid Toshiba drive and the pure SSD drive - at least, not during everyday tasks.

From a technical standpoint, there are some limits. The hybrid drive has the same SATA-III 6 Gbps interface most SSD drives have today. However, for the time being, no consumer hard drive technologies will fill this bus up completely: laptop platter disks spinning at 5400 rpm are limited in real terms to read speeds in the 100 - 120 MByte/s range, while SSDs may get up to 300-400 MByte/s. As for the hybrid drive, it has been clocked at up to 172 MByte/s read speed (http://hdd.userbenchmark.com/Toshiba-Notebook-SSHD-1TB/Rating/1957&tab=Benchmarks). However, it should be noted that results will depend on whether the data accessed is inside the SSD part, or if it needs to be retrieved from the platter. With this type of cache, we can expect best results from usage patterns that access small amounts of data that fit into the SSD part. If we need to access large amounts of varied data such as in video editing, we could expect much of this data to reside on the slower platter, thus negating the usefulness of the hybrid drive concept. On the other hand, a small, compact, operating system used for Internet access and light office tasks is ideal - and this is just about the projected use of a netbook with Xubuntu. Most system applications and user data fit within the 8 GigaByte cache and are accessed at SSD speeds. Other, larger and less-often accessed data stay within the 1 TeraByte platter and are accessed when necessary, though at a slower pace. All in all, this concept of hybrid drive is probably a very pertinent upgrade for your netbook, though perhaps less so for a tower computer that could fit in an extra SSD as well as the original disk.