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Windows PC Tuning: Improving Disk I/O Performance

PC Performance Tuning: Improving Disk I/O PerformanceThe fundamental weak link in any computer system is the Disk drive: Disk I/O performance tuning, as well reducing File accesses, mainly involves reducing the size and the number of files on the Disk drives.

You should carry out ALL of the following Disk maintenance steps – and do so frequently.

You will be amazed at the difference to your computer. Response times will return almost like the day you bought the PC.

Disk I/O Performance: Free Space guidelines

The C: Disk drive should NEVER be more than 70% full. Even between 50% and 70% full is unhealthy. I know that this means lots of wasted gigabytes, but that is a price you need to pay for good response times. Anyway, Disk drives are cheap – much cheaper than buying a new computer.

Here are the Free Space guidelines:

  • 15% Free Space is needed for the Disk Defragmenter to run
  • 30% Free Space is the minimum for reasonable response times
  • 50% Free Space provides optimal performance.

In Windows Explorer, right click the "C:" Disk drive. Then click Properties. You will see a colourful pie graph that will quickly show how full the drive is.

If you have multiple RAID Disk drives, the Free Space guidelines can be relaxed.

Disk I/O Performance: Remove Junk files

On the same tab, you will see a button "Disk Cleanup". Click it, and it will calculate how much junk can be deleted. This will include Internet files like Cookies (you can easily accumulate a megabyte each time you access the Internet), Temporary files, Set-up files, the Recycle bin, etc.

There is not much to gain from Compressing old files. There will be little improvement in the available free Disk space, and the compressed files will be slower to open. Any space saved will come from text-based files, but the real space guzzlers, like music and video files, are usually already compressed. Use the compress option only if the files are large, seldom used, and on a separate Disk drive.

Click the "OK" button to remove the Junk files.

Disk I/O Performance: Search for Old Files

Do a search using Windows Explorer's search facility, of all files (use *.*) which are more than 2 years old. Delete most of them – you have not used them for 2 years! Warning – delete your own files, not system files.

All deleted files are sent to the Recycle bin – you can recover any file inadvertently deleted. Wait a few weeks before emptying your Recycle bin.

Disk I/O Performance: Search for Large Files

Do a search using Windows Explorer again, listing all files of more than say 1,000 kilobytes. Keep only the ones that you really, really do want on-line. Those files that you do not want immediate access to, and which are more than 2 years old, should be stored off-line to a CD. To sort the files in Date order, click the "Modified" column.

One culprit is often Outlook.pst – where your Outlook emails are stored. You may need to delete the attachments to messages – pretty pictures and videos can be several megabytes in size. When you have finished the deletions, you will need to compact Outlook.pst – otherwise it will stay the same size. When in Outlook, select File/Data File Management/Settings and click "Compact Now".

Disk I/O Performance: Delete system log files

Do a search for all "*.log" files. If you have logging enabled, these files can accumulate quickly.

Disk I/O Performance: Delete Temporary Files

Use Windows Explorer to open the folder C:\Windows\Temp. The files in this folder can accumulate quickly. Delete all files older than one week.

Disk I/O Performance: Buy another Disk Drive

You will get much better throughput from two Disk drives. The advantages are:

  • It increases the free space on your C: drive.
  • It allows you to split the files logically into Operating System files and your personal files.
  • It allows simultaneous access to both Disk drives, providing better throughput.
  • When upgrading to a new Operating System, there is less chance that your personal files will be lost.

Think about buying a new solid-state drive (SSD) for the Windows Operating System. These drives are beginning to drop in price and can improve response times dramatically. Defragmenting these drives is not necessary, but will shorten their life.

Whatever you do, don't be talked into a single large Disk drive instead of two smaller Disk drives. There is also little throughput advantage in having three or more Disk drives – unless they are RAID drives.

If you have multiple Disk drives, make sure that the activity on each drive, as well as the files loaded, is in balance.

Disk I/O Performance: Remove unused Programs

Use the "Programs and Features" routine to see what programs have been installed on your system (you will find it in Start/Settings/Control Panel). Then uninstall any software no longer in use.

Files relating to the uninstalled program frequently remain, so open the Program Files folder and search for the uninstalled Program name, and delete the folder and contents. But make sure that the program has been uninstalled before any deletions with Windows Explorer.

Disk I/O Performance: Clear Logged Events

The Event log file records can number in the hundreds of thousands. Each new entry is mostly fragmented when appended, and this can degrade access times.

The Event Logs records should be periodically removed:

  • Click Start and search for 'Events'
  • Click 'View event logs'
  • Expand 'Windows Logs'
  • Right click each item and click "Clear Log..."
  • Click 'Clear'

Disk I/O Performance: Defragmentation is essential

After a while, the data files that reside on a Disk drive get spread further and further from the centre of the Disk. The files that reside furthest will have slow access times – up to 10 times slower than a well placed file. Also, files are frequently split into smaller parcels (extents in computer jargon) to allow them to slot into the available, scattered free space. The time to access 100 or more extents will be slow.

My Vista computer is a powerful 64 bit dual processor with 4 GB of memory. On Upgrading to Windows 7, I thought that the computer would be very fast. Instead it was very, very slow. I checked on Disk usage, and found that temporary folders remained - namely $Windows and $INPLACE. These were soon deleted and the Recycle bin cleared. I then defragmented the C: Disk drive. And for good measure, I defragmented the drive once again. And voila! Response times improved dramatically.

Windows 7 allows defragmentation to be easily scheduled:

  • In Windows Explorer, right click the C: drive
  • Select Properties
  • Select the Tool tag
  • Click Defragment Now
  • Click Schedule

You should schedule the Defragmenter to run at least once a week.

Disk I/O Performance: Regular Maintenance

The suggested Disk maintenance steps should be carried out regularly. You will be amazed at the difference to your computer. Response times will return to that of a new PC (almost!).

Disk I/O Performance: Minimise Disk Seek Time

The Seek Time of a hard Disk is the amount of time required for the read/write heads to move between the tracks of a Disk. Disk Seek Time is one of the most important performance indicators. Even a small reduction in the seek time can result in a large overall system performance improvement.

The Seek Time is shown in milliseconds. Here comparisons of the average seek times for Disk drives:

Seek Time
Ancient Disk drives
35 ms
Older Disk drives
20 ms
IDE/ATA drives
8 - 10 ms
SCSI drives
4 ms
SSD drives
0 ms

The actual Seek Time for accessing files depend upon how scattered the files are, and how close the files are to the centre of the platter. A lightly loaded Disk drive will always perform better than a full Disk drive – however well the files have been defragmented.

Disk I/O Performance: RAID Disk Drives

Where high volume transactions are involved, balancing the Disk I/O will be much easier using the RAID technology. RAID (redundant array of independent Disks) allow files to be evenly distributed across the drives.

The system Disk should be kept separate.

Disk I/O Performance: Solid State Disk drives

The faster your hard Disk drives are the better will be the performance. For a huge boost in responsiveness, you need a Solid State Disk (SSD) drive. Everything will be noticeably faster – all actions will be nearly instantaneous. The computer will boot faster, install faster, shut-down faster, launch processes faster.

The second generation of SSDs are now available, overcoming problems of different read/write performance and write cycle reliability. The SSDs consume less power and are more tolerant of temperature and vibration variations. Note that older versions of Windows are optimised for hard Disk drives – only Windows 7 is optimised for SSDs.

Disk I/O Performance: Hybrid Disk Drives

A Hybrid Disk drive combines the features of a Hard Disk drive and a Solid State drive (SSD) in one unit. The hybrid drive, with up to 256MB of on-board flash, performs like an SSD. Hybrid Disk drives are also reliable and cost-effective.

There will be a noticeable improvement in performance – irrespective of the age of the PC or Windows Operating System. This is a cheap, quick and easy way of improving the performance of a computer.