My daughter uses an older MacBook (1.83 GHz) with OS 10.5.6 and Parallels to run Windows applications that she needs to interface with the systems at her company. She has never defragged the drive or used any ‘tune up’ software like TechTools.

If she does, are there any special concerns related to the fact that she uses Parallels?

She backs up using Time Machine but it worries me a bit that she isn’t doing any crash avoidance.

ryck

I have a client using 4 Macs with Parallels/WinXP. None have found any uses for Windows specific third party utilities. They simply maintain there Macs with the usual common Mac third party utilities.

While programs like TechTool and DiskWarrior are certainly useful maintenance tools, I haven't found defragging the hard drive to be all that necessary on current Mac systems. Certainly not like it is in say, Windows XP.


Not really, other than the fact that the Windows side needs to be protected the same way a real PC running Windows would. That could include defragging within Windows (Parallels) periodically. Be sure to have antivirus software running on it and take any precautions you would with a normal PC, especially if she uses it to access the Internet.

Since Parallels creates a virtual hard drive for Windows that's stored inside a file, the Windows "hard drive" is just an ordinary file from the Mac's perspective. It can be backed up kist like any other file, and if something happens on the Windows side (such as a virus infection) it can be restored just like any other file.

It's my understanding that Windows defragging utilities don't actually defrag the virtual hard disk at all. They run, but since they're working inside a container file, they don't actually move anything around.

The advice to run antivirus software on the Windows side is good; it's just as prone to virus infection as a 'real' Windows PC.

I have defragged my hard drive several times and it has never had any ill effect on my Parallels virtual machine.

Not entirely the case. Just like the OS on a physical disk takes longer to seek for fragmented files, it still takes longer to seek fragmented files within a virtual disk (which resides on a large portion of a physical disk). However, in many cases there is no truly-noticeable difference. I would expect that to be the case with most Windows VM on Mac users, who tend to use their Windows installations for very specific tasks. However, in general with heavily used VMs, most experts recommend defragging virtual disks for performance optimization (although clearly physical disks benefit much greater). The benefits in a server environment, for example, can be measurable. Anyhow, I'd agree that most Parallels users prob needn't bother.

I run the Parallels Compressor once or twice a month. I believe it does defrag the VM drive file prior to doing the compression. At least it says that it does.

Nifty. Not being a Parallels user myself, had no idea they had that feature built in.

That's true, but I don't think the Windows defragger actually moves any files or directory entries within the virtual container file. It's my understanding that the Parallels hypervisor abstracts file I/O from Windows to such an extent that when the Windows defragger attempts to move a file, the Parallels hypervisor merely discards those commands without changing anything inside the container. I might be wrong about that, but I seem to recall reading that that's the case--if you look at the container file before and after running a Windows defrag program, the container file hasn't changed.

Interesting, because that's not the case with VMware, so I'd just assumed Parallels was the same. With VMware, while the actual VMDK file is contiguous, data within the container is certainly not. Therefore defrag is still applicable. If you defrag a VMware VM, you'll see the container changes a lot. This is very noticeable with an incremental or differential backup, for example.

A cursory glance at the Parallels.com forums shows some threads recommending defrag, but I haven't dug deep enough there to see if they're just doing it because they think they should vs they really should. I did find a thread in MFIF where JMB says he didn't see defrag do anything in Parallels.

since the parallels disk image is much the same as a physical hard drive in how it's used, defragmenting within Windows still has the same value as it did with physical disc.