VMs on an external HDD

Quick question

I’ve only ever run VMs (Parallels) on internal drives. Any gotchas I need to be aware of running VMs from an external hard drive?


Been doing it for years with never a hiccup.

Cool - I’m a bit concerned about speed - I don’t have an SSD external.

Suck it and see I suppose


I have about a dozen VM’s of various OS’s and I keep the lesser used ones on my external Drobo (RAID drive). Definitely slower than the internal drive (which isn’t SSD) but not to the point where I want to kill anyone. If I’m going to be using it for any length of time I’ll move it to the internal drive.

My internal SSD isn’t that big to put a lot on it but what’s there is pretty zippy. All the apps, including Xojo are on it. If you can afford the external SSD it will probably be well worth the expense with the VM’s.

Someone was posting the other day that VMWare VM’s are easier to move around than Parallels. Not sure if that’s true or not but it might be something to be aware of (since I tend to move mine around as needed to get the best speed).

The thing that took me a while to figure out is to make sure I have 2 cores allocated to the VM otherwise it’s performance will suck. Allocating at least 4 GB of Ram is good too.

That’s great - thanks Bob

May invest in the SSD external…

I have my main windows VM running on an Akitio Palm raid. It’s not cheap but it’s actually so fast it’s as good as internal and it’s redundant.

The main things to watch for are Yosemite ejecting the drive. I have eventually had to disable allpower saving
And you can’t use time machine for the external drive.

I’m a tad concerned about the lack of thunderbolt on the latest MBP now though as I use the palm raid to take my VM on the road with me.

[quote=192165:@Patrick Delaney]Cool - I’m a bit concerned about speed - I don’t have an SSD external.

Suck it and see I suppose

The solution I used was to get a thunderbolt external drive enclosure. The drive’s hot enough to cook on, but the VMs are really fast :stuck_out_tongue:

Not sure I’m interested in cooking a hard drive! Tough Eating!!

ok… related question.
I have an iMac with a 1TB internal HD, and a SanDisk enclosure with 3 different HD’s (1TB, and 2 400gig), leaving me one free slot in that box. This connects to the iMac via USB3.0 …

Would it be worthwhile to install an SSD in the 4th slot in the external enclosure. For some reason I have it in my head that SSD don’t work well over USB3…

I use multiple 2TB Lacie Thunderbolt drives running various VM’s. It’s fast enough for day to day things.

I use an external Thunderbolt enclosure (Akitio Thunderbolt-2 Mini) with 2 512g SSDs and two spinning 4tb 2.5" drives. I combine the SSDs and the spinning drives into Fusion Drives, and the speed from them is quite respectable. A little slower than the internal Flash, but still rocking. (Internal Apple Flash is about 800MBs, externals are 570MBs or so, until you run them out of SSD space.)

It runs cool and quiet, and I am seriously contemplating unplugging the fan in the enclosure. I tried the enclosure with four 256GB SSDs in it, and striped all four drives into a RAID-0 configuration. Speeds were fantastic, well above 1000MBs. I don’t think anyone would have trouble running a VM on drive space like that. I needed the extra space to house VMs and sample data though, and the Fusion Drive setup is plenty fast to improve my productivity quite significantly.

That replaced a Thunderbolt-1 enclosure that housed two 128G SSDs and two 1tb drives, which was significantly slower and generated much much more heat. On top of it, the T2 setup cost less too. I do love the way technology advances in this age! :slight_smile:

I use an external thunderbolt with a 512GB SSD. I went with the LaCie (orange ones) as it is small and rugged if I want to take it on the road. SSDs are great until you need to spend any length of time on a workstation without one. You get spoiled!

discounting ThunderBolt… is using an SSD over USB3 worthwhile?

You’ll see a bit of sluggish ness if the VM has to swap a lot but its still quite useable

i’m looking for a new 512GB SSD,
can anyone help me to find the best one?

I have been running several computers including a data server on Samsung Evo drives for 4 years now. Not a single failure. I know other people have had a very different experience. I also had very good performance from a Crucial drive.

Tom’s Hardware seems to still recommend the Samsung drives for most segments.

The thing with SSD drives is that they will not give any warning before failing. Make sure you have a good backup procedure in place. Also, never defrag a SSD drive. You will not gain performance and you will reduce the drive’s life expectancy.

Fast the bus speed the better off you are. USB3 is very usable unless the VM’s O/S is swapping lots. USB2 is usable but USB3 is better. For many years I ran lightweight VMs off a HD (spinning drive) via USB1. Useable but at times a little slow.

the speed will be as fast as the slowest link.

Now the one thing I will warn you about is you need to be careful which USB port you plug into. the ASIC (chip) that controls the port will run as fast as the slowest device on the ASIC. So if you have 4 ports (2 on each side of a laptop, there is probably 2 ASICs - one on each side). so if you plug in a keyboard in one port and the SSD into the other, the SSD will run slow due to the ASIC having to baud down to the slowest link. That is why on my intel/windows/linux laptops, I plug all my mice/keyboards/slowstuff on one side and my drives (USB3 for the most part) on the other.

this is relative. Crucial, Samsung, Intel, and a few others are good brands. I have a new Intel series SSD and it smokingly fast and reliable. I have a lot of Crucial M series in Macs/Linux machines and they are awesome too.

Since we are on the subject, has anyone used the Highpoint Rocketsor 5212?


I believe OWC also makes a similar device now, too… but much more expensive.

I have the new Mac Pro (cylinder) and have heard horror stories about the USB3 performance with multiple USB drives so I’ve been looking at thunderbolt enclosures but they are not cheap. Was thinking about sticking an SSD or two in one of these.

I have been running virtual machines on those:

link text

The speed is really really awesome. I have seen after I got that one that are are also now USB 3.1 cases that take M2 SSD in them (which is basically what this one does internally, except this one is not customisable). Big mistake when having SSD externally is to have Sata based SSD since SATA is really the bottleneck.