Solid state disks (SSDs) offer real speed, low power consumption, and a compact form factor. They make costly but terrific system disks, though it takes some effort to migrate onto an SSD from a conventional hard disk. This article shows you how to make that transition for your end users or customers, with special notes for Windows 7.
Solid state disks, usually called SSDs, replace spinning magnetic platters and movable drive heads with arrays of nonvolatile flash memory for storage. Instead of addressing disk locations by head, cylinder, and sector as on spinning disks, SSDs use memory addresses to denote starting points for data elements.
How SSDs Work
SSDs are faster than conventional spinning drives because they have no moving parts. Instead of waiting for read/write heads to get into the right position on a platter, then waiting for the desired data location to literally “come around,” SSDs access data more or less instantly by jumping from one numerical memory address to another. That’s why fast conventional disk drives have average “drive latency” values of 10–15 milliseconds — the time it takes for everything to get into position to start reading or writing — whereas SSD latency is typically rated at 0.1 milliseconds.
SSDs emulate hard disks inside memory banks under their exclusive control. Most SSDs sold today emulate the serial ATA (SATA) drive interface, and are plug-compatible with conventional SATA hard disks — only faster. SSDs also typically consume less power than conventional hard disks, which must power up motors to spin platters and move heads around. A typical hard disk consumes anywhere from 0.6W at idle (not in use) to as much as 5.5W for high-speed operation for notebook drives, to double that on desktop or server drives. A typical SSD consumes less than 1W when idle (values from 0.2 to 0.4W are normal, though some may be as high as 0.9W) and seldom more than 2W when reading or writing. This means that SSDs consume far less power than conventional disks. This is nice on desktops where power is readily available, but wonderful on notebook PCs where battery life gets a boost any time power consumption drops.
SSDs aren’t quite as simple or straightforward as “replacing spinning disks with flash memory” might suggest. Because drives are meant to be written, read, and rewritten repeatedly, SSD makers must watch where they write information and level out their use of storage locations across the drive. That’s because flash memory becomes less reliable when individual storage locations are written to more than 10,000 times. The drive controller keeps track of usage, and works actively to average usage out across the disk. SSD drive controllers often subdivide a large logical drive into numerous smaller physical drives so read/write activity can be distributed and operated in parallel. This helps to explain why typical speeds for conventional hard disks seldom exceed 70 megabytes per second (MBps) for read and 35 MBps for write, where SSDs deliver 150 MBps or more when reading, and 70-plus MBps when writing.
SSDs are also expensive. Byte for byte, they cost at least six times the usual price of conventional hard disks. You can buy a reasonably fast 1 terabyte (TB) hard disk for $80 at the moment, whereas the least- expensive 80 GB SSD currently available costs $200. The numbers average out to $2.50 per GB for SSD versus 7.8 cents per GB for conventional hard disks, a ratio of over 32 to 1.
But if you can cover these costs, you’ll get a faster PC in the bargain. Notebook owners also benefit from increased battery life; how much life depends on battery size and normal usage patterns, but increases ranging from 15 minutes to an hour are normal.
Moving from a Conventional Drive to an SSD
Given typical costs and sizes for both kinds of drives, it’s certain that such a move means going from a larger drive to a smaller one. Because speeding up the system disk (which is often the only disk in a notebook PC and the primary disk in a desktop PC) provides the biggest benefits, it’s most likely candidate. Downsizing the contents of this drive therefore becomes a key priority.
Cleaning Up the System Disk
The first task in the transition is to reduce the amount of space in use on the source system disk, which involves examining folders on that disk to decide what can go and what must stay. (I use Windows as an example because it covers more than 90% of desktops.) The following folders will invariably remain on a Windows system disk for Windows XP, Windows Vista, and Windows 7 even on an SSD:
- Documents and Settings: A standard folder maintained for backward compatibility on Windows Vista and Windows 7. You’ll usually leave this folder alone.
- Program Files: Where Windows puts programs you install on your PC. Examine installed programs carefully, and uninstall what is not needed or never used. Do this in the Programs and Features applet in Control Panel, or use the free and excellent Revo Uninstaller (www.revouninstaller.com).
- Program Data: Where Windows stores data files for the programs installed in Program Files. You’ll generally leave this alone.
- System Volume Information: Not accessible via Windows Explorer, but you’ll learn how to pare this down in the next section.
- Users: Where user account files and information are stored. Access any accounts on the PC that you can, and move or delete all unnecessary or unwanted files.
- Windows: Where the Windows OS resides, and all of its files, updates, and utilities. You’ll generally leave this alone, too.
Any other folders are fair game for relocation or deletion on a system disk. When I cleaned the system disks on my two test systems, I was able to reduce space by 4 to 12 GB using this technique.
Using disk cleanup tools can also recover disk space. (To run Disk Cleanup, for example, right-click the system drive icon inside Windows Explorer, choose Properties, then click the Disk Cleanup button.) When I ran this tool on my test PCs, I freed up 1 to 4 GB of disk space.
Tip: Be sure to click the Cleanup System Files button to maximize your savings potential.
By far, the biggest consumer of disk space on Windows Vista and Windows 7 system disks is for shadow copies. These include restore points and other shadow copies that Windows creates automatically — at least once a day for restore points, or whenever you install software that’s smart enough to take these system snapshots. Windows Vista claims 15% of a disk for shadow copies, and Windows 7 claims 5% on all system drives. For a 400 GB drive (which is really 362 GB in binary), that means 55 GB for Windows Vista and 18 GB for Windows 7. If you’re moving from a drive of that size to an 80 GB SSD, those values must be reduced to match the new target drive (12 GB for Vista, 4 GB for Windows 7) before you migrate. This has a huge impact on the drive image size you’ll move from your conventional hard disk to an SSD, so it’s a key step in the transition process.
Here’s how to trim volume shadow storage allocations:
- Open a command window with administrative privileges in Windows Vista or Windows 7 (select Start, All Programs, Accessories, right-click Command Prompt and select Run as administrator from the pop-up menu).
- Type the following command:
vssadmin resize shadowstorage /For=C: /On=C: /Maxsize=XXGBwhere XX is 15% of the size of your SSD for Vista, or 5% for Windows 7.
This removed 40 GB of space on my test units, and will do likewise on most desktop or notebook PCs.
How Big Is Your System Volume?
Conventional wisdom dictates that a system disk should include at least 25% free space. SSDs don’t need to be defragmented, and Windows 7 is smart enough to turn off ReadyBoot, ReadyBoost, and SuperFetch on SSDs. For an 80 GB SSD, trim your system disk to no more than 60 GB, so that at least 20 GB remains available. Here’s what the system SSD looks like on my primary desktop:
Moving from Conventional HD to SSD
Once you’ve trimmed your system disk, moving over to the SSD is absurdly easy. You’ll need a third-party backup program, however, because neither Windows Vista nor Windows 7 lets you choose where to restore a system image. (The OS decides, and seldom picks the target you want.) I used Acronis True Image Home 2010, but you can use a free program like DriveImage XML if you prefer. Your tool must create an image backup of your system drive, then restore that backup to your new SSD.
Using the tool, create an image of your system drive, which is C: on most Windows PCs, on a target disk of your choosing. (Make sure the target disk has enough free space to accommodate the source drive image.) Next, restore that image to your SSD. If your SSD hasn’t been formatted, you must do that beforehand to make the drive accessible to your backup tool.
Once your system image is ensconced on your SSD, remove your current system drive and install the SSD in its place. Usually, removing the old drive and using the same power and data cables on the SSD gets this job done. If you can’t boot your system afterwards, don’t panic. Reboot your PC, then access its BIOS (by pressing the Delete key at startup, on most machines) and make sure the boot order elects the SSD where the old hard disk used to be. After that, you should be good to go!