How slow should Parallels be with Win2K on a Mac Mini?

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bhawthorne

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I am running Parallels with a Windows 2000 VM installed on a Mac Mini (1.83GHz Core 2 Duo with 1 Gb of RAM). It is almost unusably slow. I used the transporter to copy my system from a 5-year old Dell Optiplex that always ran just fine.

The Parallels configuration is the latest version and all default settings. It is slow whether I run in full screen or coherence mode. The VM is installed on a fast USB2 external drive, and the drive seems to be working pretty hard as soon as I run Parallels.

There is 256Mb of memory allocated in the configuration, which is the "optimal" amount according to the configuration editor. I tried upping that to 512Mb, and not only was Parallels even slower, but everything else on the Mac suddenly became unusable too.

Do I need to buy another Gb of RAM for my Mini, or is there some secret to making this work?
 
You could try copying the VM Disk image to the internal HD. If your Windows VM has to little memory, it may have to use a lot of virtual memory. If the VM disk image is on a slow hard drive, this could cause a big slowdown.

If you increase the memory for the virtual machine, always keep an eye on Activity Viewer in MacOS X. Make sure there's enough memory left. (as soon as there's no more memory free, MacOS hast to start paging out, and that's what makes your computer incredibly slow)

It may seem obvious, but try quitting all other applications on the mac, so that parallels is running alone. especially apps like safari or itunes can use huge amounts of memory, that your virtual machine would need.

hower 1gb of ram seems very little to me -- you''ll probably see big speed improvements if you get another gig.
 
But how fast should it be, really?

My internal drive does not have enough free space to hold the disk image (70Gb, since I haven't figured out how to make it smaller after moving data files out). The external drive is faster than the internal, and the USB/2 transfer speed should be pretty close.

Longer term, I can try adding more memory, but I'm trying to figure out if Win2K running on a 1.83GHz Core 2 Duo is supposed to be at least 10 times slower than it was running on a Dell 400MHz P4. I understand that things are going to be a bit slower with the virtualization, but the CPU is at least 5 times as fast. Heck, Windows is running slower on this computer than it used to run on my 667MHz G4 PowerMac running VirtualPC! That was at least usable.

I just want to know is this expected? My system seems to fit easily into the system requirements that Parallels lists on their web site.

So, am I doing something wrong, is this expected behavior, or is there some bug? Should I give up and switch to Boot Camp?
 
No, it definitely isn't supposed to be 10x slower than on the 400MHz Dell, but of course it always depends on what you're trying to do.

How much memory did you have on the Dell? I'm still pretty sure, that your problems are memory related. I have a copy of Win2k3 running on a MacMini (ICD 2.0 Ghz, 2GB RAM) and it runs just fine.

You can test the performance of your USB 2.0 external drive using a utility such as Xbench, and compare it to your internal drive. That way you'll see if the USB connection is the bottleneck. You're mostly interested in random access performance.

And then there remains the problem of RAM. I don't know how much RAM is suggested for the usage of Parallels, but I did see big speedups when I upgraded from one gig to two, especially when running multiple apps on the mac side.

making the harddrive smaller can be accomplished using the parallels tools.
 
The USB Hard disk is probably the issue.

While the transfer time is definately comparable to the internal drives on a 400mhz Dell, the IOs per second (number of disk commands per second) of USB2 is far less then that of IDE even on older boxes.

When using a drive for storage of very large files (such as backup drives, media drives, etc) nobody notices this as the amount of disk commands are tiny compared to the transfer time, however when working with small files (like OS system files) the drive command time is much greater then the transfer time and it becomes noticable.

See this page for more information

Is your drive able to connect through firewire? This would greatly reduce the problem.

The RAM might also be an issue, check the "Activity Monitor" applications under utilities. Apple reports free RAM differently then PCs do.

"Free RAM on WinXP" = "Inactive RAM on Mac" + "Free Ram on Mac".

The easiest way to see if you need more RAM is to look at the "Page Outs" after the machine has been running for a while under normal use, it should be a small number. My MBP has been running for about 2 or 3 days since it installed the safari update, it has 124KB of "Page Outs". A small number of KB or MB per day is normal. Hundreds of MB (or GB!) means you need more RAM.
 
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For detailed instructions on how to compress the disk image file of your Virtual machine, see "Using Parallels Compressor" in the Parallels Desktop for Mac User Guide PDF file, located in the Parallels Desktop Application folder.

As stated above, USB is a lot slower than built-in hard drives or Firewire drives, especially for small reads/writes. And if your virtual machine has to use alot of Virtual Memory because there isn't enough RAM, thats what really kills performance.

Did you try a hard drive benchmark with XBench yet, to compare the USB disk with your internal hard drive? You can get XBench at www.xbench.com. You should look especially at the random access performance for small blocks.
 
It must be a RAM problem. I just looked at again at the Parallels system requirements, and realized I got suckered in by marketing speak. I have a 1-gig system, and I thought that's was well within their system requirements. In fact, their requirements say "Memory Requirements 512 MB minimum available memory (1 GB recommended). Support for any memory configuration (up to 16 GB), without modifying your host system."

Note "available" memory. Looks like I need to add another GB so I'll have at least 1Gb available to assign to Parallels.

By the way, thanks for the advice on running XBench. My external drive gets an overall score of 33.46 vs. 30.27 for the internal drive. On the random access part, 35.27 external vs. 19.78 internal.
 
Yeah, I agree to the RAM problem hypothesis... Usually if things are crawling slow you have viruses, a memory leak in Parallels Tools, or (the most likely) improper RAM set-up.

You should have at least 2 GB of RAM for a smooth experience with Parallels, more if you use RAM intensive applications either on Windows or on OS X at the same time you are running Parallels. Also, unless you are using memory intensive applications on Windows, between 512 MB and 768 MB of RAM for Windows XP is the sweet-spot, Windows 2K should be similar or a little lower (memory usage is typically more efficient as time/versions go on).
 
$75 for 4Gb (2x2Gb) of RAM later... (Mac Mini can only address 3Gb, but 4Gb was about the same price and apparently there is a benefit in video performance with matched DIMMs. Don't ask about what it was like opening the Mac Mini.) In any case, installed the memory and assigned 1Gb of it to Parallels, which now runs quite acceptably. Whew! I really did not want to have to use Boot Camp.

Thanks for everyone's help!
 
Too little disk space

bhawthorne said:
My internal drive does not have enough free space to hold the disk image (70Gb, since I haven't figured out how to make it smaller after moving data files out). The external drive is faster than the internal, and the USB/2 transfer speed should be pretty close.?
Click to expand...

Good that things are now OK:

You might try to set up a fresh VM with Windows 2000 on your hard disk and then slowly migrate the programmes that you really need. You can always keep some of the data on your external drive. This is the way I will be going in the future.

Good luck and please post your success story.
 
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