SSD transfert rate issue in use, but not in test

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SSD transfert rate issue in use, but not in test

Postby pierre_A » 2018-02-13 19:57

Hi,

I have an old 128GB SSD that i use as an external drive in a eSATA case.

When I copy a lot of data on it, after some time, the transfer rate drops below 1 MBps, just like if the cache would be full.
If i launch a test using the disk program in Gnome3, the transfert rate is 200 MBps read / 120MBps write, even with a hundred 1000MB samples.

What is happening ?
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Re: SSD transfert rate issue in use, but not in test

Postby peter_irich » 2018-02-13 20:12

Try copy one big file by size 1GB or more and compare result.

Peter.
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Re: SSD transfert rate issue in use, but not in test

Postby pierre_A » 2018-02-13 20:47

Code: Select all
time cp big1700MBfile mySSD

real   0m15,065s
user   0m0,008s
sys   0m1,092s


That's about 110MBps

I think the problem happen when transfering a lot of small files.

The SSD is software encrypted, don't know if this is important.
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Re: SSD transfert rate issue in use, but not in test

Postby pawRoot » 2018-02-13 20:51

Not sure about your issue but when i encrypt my SSD via Debian installer, the system is much less responsive.
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Re: SSD transfert rate issue in use, but not in test

Postby pierre_A » 2018-02-13 20:59

The SSD is encrypted using LUKS.

All my laptops are encrypted, I haven't noticed any performance issues (although the CPU is much less powerful on laptops than on the desktop i am using with the external drive)
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