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I want to run Win10 from a USB flash drive but I want it to run fast. I found a specific product and it can r/w sequentiallly 245/190 MBps which is more than some SSDs are capable of. Although I don't have information about the non-sequential performance which is critical for system disks as far as I know.

I know that Linux is capable of running quickly on almost any kind of drive but Windows is very very sensitive to drive performance and becomes unusably slow on a regular performance drive.

Is such a fast pendrive a good choice for a system disk? I want Windows to run faster than on an HDD would and almost as fast as a built-in SSD would be.

By good choice I mean that the system would be able to perform a complete boot process under one minute and start Adobe Photoshop under 5-10 seconds.

I'm also looking fot personal experiences with running Windows from a flash drive.

Nandor
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  • Your question is off-topic. A common mistake made by new members is failing to reading what is [on-topic](http://superuser.com/help/on-topic) before posting a question. You should become familiar with the site by taking a *[tour]* and reading *[ask]*. – CharlieRB Apr 12 '16 at 12:28
  • OK, I'm guessing the problem is I named the product. Fine, I will edit it out. – Nandor Apr 12 '16 at 12:31
  • No! Don't guess. Please read what is on topic here. I specifically gave you a link so you can learn how to use the site properly. Asking for product recommendations is not allowed. – CharlieRB Apr 12 '16 at 12:34
  • I read it, thank you for the link. Though my question wasn't really about that specific product but the problem of running Windows from a pendrive. It wasn't clear though so I edited. – Nandor Apr 12 '16 at 12:36
  • The reason I named the product in the first place is because I know that there are said-to-be fast flash drives which perform INCREDIBLY bad as a windows system disk. But I don't have experience with the fastest one and I don't want to purchase it unless I know it will be a good pick. – Nandor Apr 12 '16 at 12:39
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    IMO, the problem is not you mentioning the product by name, the problem is that we can't tell you what's good enough for you. Get a drive, [install Windows](http://superuser.com/questions/960558/windows-os-on-external-hard-drive), see if it's fast enough for your usage. As-is you're just asking for opinion, voting to close as such. – Ƭᴇcʜιᴇ007 Apr 12 '16 at 12:43
  • It is not that you named the product. That is actually helpful. It is that you are asking if that product is a good choice. In other words, you are asking us if you should buy it and use it. That is a product recommendation and also asks for opinions and can cause debate. – CharlieRB Apr 12 '16 at 12:43
  • Alright I get it now. I edited and hope that it's non-subjective now. – Nandor Apr 12 '16 at 12:47
  • A pen drive will not last long running an OS from it, constant read writes will kill it fast. – Moab Apr 12 '16 at 18:27

1 Answers1

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Is such a fast pendrive a good choice for a system disk?

Fast is always good. Based on the sequential speeds alone, there's no reason to not choose it.

Overall however it's hard to tell, because as you've said yourself, random and small-block I/O performance is quite important, and you don't have that information available.

It is however usually possible to find the appropriate information online if you look hard enough - particularly common applications such as IOMeter, AS SSD, and CrystalDiskMark are used for these purposes, and searching for, e.g. "Crystaldiskmark (name-of-drive)" may give you information on the random R/W performance.

As an example, this gives information on a Lexar P20 drive, this provides similar info on a Sandisk Extreme drive, and this provides information on a fairly mediocre internal SSD, and this provides results for a fairly dated, low-end internal SSD. In comparison, 7200RPM spinning hard drives can be found here

In general, what you're looking for is 4K random read/write performance:

enter image description here (Source)

In the above picture, you can see two USB drives both with very fast sequential R/W performance but one provides 0.05MB/sec random write while the other does 10.2MB/sec random write. If you refer to the five Google searches above, you'll see an old, low-end internal SSD still does around 10MB/sec random write, whereas fast modern drives do >40MB/sec read and write (internal ones often write faster than they read in random I/O). Spinning hard drives on the other hand have random 4K speeds of 0.5-1.5MB/sec in comparison.

In general you'd want to look at a USB drive that has random read/write performance of at least 3-5MB/sec. Anything above 10MB/sec is very fast as far as USB drives are concerned, the 0.05MB/sec of the Lexar in the example above is pitiful. Since running Windows is more read heavy than write heavy, 4K read is more important than 4K write. So again referring to the picture above, even the pitifully slow USB drive has 7MB/sec random read, which is 5-10x faster than a traditional hard drive.

Bear in mind, Windows To Go is specifically optimized to run from USB flash drives, so it won't be quite as slow as if said flash drive were used with a "normal" HDD/SDD standard install.

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