Read Test Results : Virtual Windows PCs on Macs

Read Test Results

By Bill Lake, published on April 13, 2007
Source: Tom's Guide US | Keywords: virtual, windows, pcs, on, macs

Contents

7. Read Test Results

Linear Read Tests

Roadkil's Disk Speed 1.1 (12 tests; reboots between each test; highest and lowest results removed; remaining results averaged)

Machine Tested	MB's Read	Elapsed Time in Seconds	Speed in MB/Sec
Boot Camp Native XP	165.7125	5.001	33.1359
Parallels VM of XP	130.0875	5.012	25.9542
Parallels VM of Boot Camp XP	70.95	5.004	14.1798

Boot Camp Native XP is the fastest in the Linear Read Test followed by a respectable Parallels VM of XP and trailed dramatically by Parallels VM of Boot Camp XP. This is pretty much how you'd expect things to work out, given the increasing distance of each machine from a native environment.

Random Read Test

Roadkil's Disk Speed 1.1 (12 tests; reboots between each test; highest and lowest results removed; remaining results averaged)

Machine Tested	MB's Read	Elapsed Time in Seconds	Speed in MB/Sec
Parallels VM of XP	14.3938	5.008	2.8744
Boot Camp Native XP	12.2625	5.008	2.4487
Parallels VM of Boot Camp XP	9.3438	5.011	1.8645

Random Read time tests favor Parallels VM of XP over Boot Camp Native XP with Parallels VM of Boot Camp XP again coming in pretty far behind. This result does not fit with expectations.

Access Time

Roadkil's Disk Speed 1.1 (12 tests; reboots between each test; highest and lowest results removed; remaining results averaged)

Machine Tested	Accesses	Elapsed Time in Seconds	Access Time (MS)
Parallels VM of XP	1192	5.010	4.20
Boot Camp Native XP	467	5.006	10.72
Parallels VM of Boot Camp XP	417.6	5.005	11.98

Access Time is spectacular for Parallels VM of XP, running at well under 5 ms. The other two "machines" show respectable laptop drive access times. Again results do not fit with expectations.

Why the anomalous results in some cases? The differences are probably due to the way Parallels runs active VMs saves and reloads VMs when you transfer to another or shut down or reboot the comptuer. VMs are stored mostly in memory while they are active and are saved with current memory data and system state. So even with a reboot, disk reads are probably being made from memory, at least after the first read.

Write Results

So the read results were somewhat of a surprise, let us see how the three "machines" write files.

Batch Write Files

Disk Bench 2.5.0.3 (10 tests, reboots between each test; results averaged)

Machine Tested	Average Write speed
Boot Camp Native XP	11.76 MB/s
Parallels VM of XP	8.763
Parallels VM of Boot Camp XP	4.825

Here we see the results we expected. Boot Camp Native XP wins the race. Parallels VM of XP gets a nice boost in reading but suffers when having to write to the virtual hard disk drive, which is really a file in OS X. Parallels VM of Boot Camp performs the worse of all three again; its performance is slowed by its being a real disk in a virtual machine environment.