Running a MBP from a flash drive

[cprescott1972]

Hello! I am trying to run a version of macOS Catalina from a flash drive on my 2020 MacBook Pro. It appears to be compatible and it was able to get it to install onto a USB-C flash drive.
The flash drive is a Sandisk Ultra 256GB usb C speeds up to 400mb/s

The only problem is every interaction with the operating system has like a 30 second delay. It makes using it basically impossible. I’m needing to install Catalina so I can run some old software that I need. Does anyone know if there’s a setting I can change on the computer to make things run more normally? Or perhaps the flash drive needs to be formatted differently? I followed the instructions on Apple‘s website carefully and everything seem to install right but it’s so slow that it’s unusable. Does anyone have any thoughts?

Thanks in advance for any ideas

 

[Bigwaff]

am trying to run a version of macOS Catalina from a flash drive on my 2020 MacBook Pro. It appears to be compatible and it was able to get it to install onto a USB-C flash drive.

Without knowing the brand, model, capacity, and USB version support of your flash drive, I’d say it’s read/write speeds are too slow.

 

[6749974]

Try an external SSD. You can get 1 TB for $85, maybe less on sale.

I'm a layman, but I think the flash drive is terrible for random read/write, which is what a boot drive would be relying on mostly. Anyway, I found this answer:

The problem is that flash-drives are quite limited in speed as compared to spinning hard-drives and SSDs. This is because by their nature, they are not meant for high-performance usage and so use simpler, more basic mechanisms than a comparable SSD or hard-drive (which is also why they are much cheaper).​

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You can (currently) expect typical read speeds <=20MBps and write speeds <=10MBps. This is usually going to be slow enough that unless you are just using it as a live-OS type of system for data-recovery and such (i.e., occasional, emergency usage), then it will be too frustrating for regular, every day usage.​

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What is worse, is that by running an OS from a flash-drive, the non-stop writes for logs and temporary files will really eat into the flash-drive’s lifespan. Don’t forget that flash-cells have a limited number of writes before they can no longer be written, and these constant writes will use them up too fast, even with wear-leveling because again, the writes and leveling used in inexpensive flash-drives is not as efficient as with SSDs (which use things like TRIM whereas flash-drives tend not to).​

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You could run an everyday OS from a flash-drive, but ones that are going to be fast enough will usually also be expensive enough that you may as well just get a cheap SSD and benefit from the enhanced wear-leveling as well.​

 

[cprescott1972]

Without knowing the brand, model, capacity, and USB version support of your flash drive, I’d say it’s read/write speeds are too slow.

I updated the post. Thanks!

The flash drive is a Sandisk Ultra 256GB usb C speeds up to 400mb/s

 

[Bigwaff]

The flash drive is a Sandisk Ultra 256GB usb C speeds up to 400mb/s

SanDisk.. bottom of the pack in the random read/write tests… that is your problem.

Best Flash Drives 2024: Fast, Roomy, Pocketable USB Storage

Recent high-end flash drives are much faster and more spacious than they used to be.

www.tomshardware.com

 

[BrianBaughn]

I agree with the recommendation of an SSD. You can get a 500GB SATA plus a USB to SATA connector for around $50 these days.

Don't waste any more time or money on the type you currently have.

 

[Fishrrman]

As others have said, get rid of the flash drive for booting/running.
Get a cheap SSD and use that instead.

Take a look at the Crucial X-9.
VERY small, but USB3.1 gen2 performance (read speeds up around 900MBps).

 

[zevrix]

Hello! I am trying to run a version of macOS Catalina from a flash drive on my 2020 MacBook Pro

Like others already mentioned, flash drives are mostly for storage and only occasional write operations. So be prepared that your drive may fail completely relatively soon (been there) and make sure to back up any important files you may have there.

 

[cprescott1972]

Sorry for the delayed response. Thanks for all the suggestions. You were all correct. The USB C Flash Drive was the culprit. I did the process again, formatting an external SSD. It's working great so far. Pretty speedy! And now expanding my ability to use a larger drive than what is installed in my MBP. Thanks all!