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USB 3.0 flash drive vs USB 3.0 external SSD

C

camner

macrumors regular
Original poster
Jun 19, 2009
245
18
I'm trying to run a Parallels VM off of an external drive since my MBA only has a 128GB SSD and the VM takes up nearly 43 GB.

I tried a PNY 128GB 3.0 flash drive, and that is essentially hopeless. Windows takes forever to boot. That's despite the fact that BlackMagic speed test shows the flash drive to have write speeds about 25% of the SSD and read speeds of about 50% of the SSD (the Windows load time is MUCH more than 4x what it is off the SSD).

Another option to consider is to take a slim USB 3.0 external 2.5" case and put a, say, 64GB SSD inside. That would be bulkier than a flash drive, of course.

Is it the device or the USB 3.0 connection is the bottleneck? Would an external SSD run much faster?
 
when you buy a usb 3 flash drive you have no idea what your are buying
you are not guaranteed what the read or write speeds are
most flash drives don't even tell you on the packaging what it is capable of


advice

consider sd cards.
when you buy an SD card you can look at the package and it will say "class 10"
and you clearly know that the expected read and write speeds are , they could be 10 MB/S or 30 MB/S depending on the card and the reader

The bad thing about sd cards is they are not backwards compatible. if you buy a sd card that is 4gb, it may not work with old sd readers from several years ago, this of course does not effect macs, but it could make your flash drive unreadable with a printer or your friends camera or windows machine

to bad macs don't have compact flash slots. they can do 120MB/s
 
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camner said:
I'm trying to run a Parallels VM off of an external drive since my MBA only has a 128GB SSD and the VM takes up nearly 43 GB.

I tried a PNY 128GB 3.0 flash drive, and that is essentially hopeless. Windows takes forever to boot. That's despite the fact that BlackMagic speed test shows the flash drive to have write speeds about 25% of the SSD and read speeds of about 50% of the SSD (the Windows load time is MUCH more than 4x what it is off the SSD).

Another option to consider is to take a slim USB 3.0 external 2.5" case and put a, say, 64GB SSD inside. That would be bulkier than a flash drive, of course.

Is it the device or the USB 3.0 connection is the bottleneck? Would an external SSD run much faster?
Click to expand...

Cheap flash disks like SD cards and most USB flash drives are horrible at randomly writing data, even if they have okay sequential read/write capability. And a lot of typical computer use is writing random data.

An SSD in an external USB enclosure will be a bajillion times faster than an SD card or 99% of USB flash drives.

In fact for a few months I was using a 1st gen SSD from ~5 years ago over a USB 2.0 connection and it still felt significantly faster than a hard drive in most cases.

I still have that disk and use it to transfer files around if I have any significant amount of data since flash drives are way too slow.
 
I plumbed a samsung 128gb SSD into a standard usb 3 case and installed windows 10. Runs super fast for external, In black magic was giving 230mb/s read and write. I think it would go faster with an optimised ssd USB 3 case. Got one on order from Amazon. Hope this helps. I did try to install on USB 3 Sandisk extreme CZ80 64gb drive with quoted speeds up to 245mb/s but it took about an hour and got nowhere so I gave up.
 
motrek said:
An SSD in an external USB enclosure will be a bajillion times faster than an SD card or 99% of USB flash drives.
Click to expand...

This. I use Sandisk usb3 thumb drives as well as a large ssd in an oyen digital usb3 enclosure.

Black Magic says I get 415 MB/s write and 411 MB/s read on the SSD (formatted ExFAT), 57 MB/s write and 180 MB/s read on the thumb drive (formatted HFS or ExFAT - no performance difference).

I know Black Magic doesn't mirror everyday computer life, but does provide a baseline.
 
The quality of the flash memory inside your typical USB flash drives is dog**** compared to a typical SSD.

If you run a speed test on them you'll see. the cheaper ones barely even break the USB 2 maximum theoretical speed.
 
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i would suggest you to have a 'thin' version of windows for your parallel VM or use only MAC os,:)
e.g. windows thin pc
 
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