Why is windows file copy so slow?

[NunoLava1998]

Each time I try to copy a file or a file full of folders, my Windows Explorer speed always tanks down to 100kb/s despite 4KQ1T1 speeds on CrystalDiskMark reaching up to 170MB/s (if i up the threads to 20, 1100MB/s). Same with robocopy.

What could be causing this? I have BitDefender 2019 antivirus, and the Optane 800P 58GB SSD.

[NunoLava1998]

It isn't exhausting the drive's cache because the Optane SSD IS literally made out of cache; and it isn't because the drive is nearly full

[jaslion]

Depends how it's configured. If it's just copying files to a hdd instead of using the optane drive correctly it will just be slow if ther is a bunch of small files to be copied as well that's how a harddrive works.

[NunoLava1998]

1 minute ago, jaslion said:

Depends how it's configured. If it's just copying files to a hdd instead of using the optane drive correctly it will just be slow if ther is a bunch of small files to be copied as well that's how a harddrive works.

It's an Optane SSD. It's not being used as cache for an HDD; and isn't meant for that. You can tell as there are no 58GB Optane Memory modules (which are for caching HDDs)

[jaslion]

There are plenty of the 64GiB (58GB) optane caching modules out there. Depending on your copy even an ssd will tank if it's a buttload of tiny files being copied. Not much you can do about that. If you copy one big file (like a movie or something) you'll see the correct performance. Are you copying this to the same drive or another one?

[NunoLava1998]

1 minute ago, jaslion said:

There are plenty of the 64GiB (58GB) optane caching modules out there. Depending on your copy even an ssd will tank if it's a buttload of tiny files being copied. Not much you can do about that. If you copy one big file (like a movie or something) you'll see the correct performance. Are you copying this to the same drive or another one?

It's 58GiB, not 58GB. There is the M10 64GB which is 64GiB. It's the same drive.

You do say that; however I see other people copying with Windows Explorer on i.e. NVMe drives and it just staying up there at 1GB/s with lots of small files. It shouldn't tank that hard, too; the 4K speeds are literally 170MB/s; why would it tank 1700x?

 

Also; i ran a 16GB test on crystaldiskmark and it ran just fine

[homeap5]

Do not look at speed measurement for small files - it will show you low values or false values. Speed measurement needs time and bigger file to be accurate. Lot of small files needs more operations than just copying bytes. Filesystem must allocate space, file table must be update, attributes must be set, permissions must be set etc.

[NunoLava1998]

12 minutes ago, homeap5 said:

Do not look at speed measurement for small files - it will show you low values or false values. Speed measurement needs time and bigger file to be accurate. Lot of small files needs more operations than just copying bytes. Filesystem must allocate space, file table must be update, attributes must be set, permissions must be set etc.

CrystalDiskMark 4K testing does literally the exact same stuff I'm trying to do though

[NunoLava1998]

1 minute ago, NunoLava1998 said:

CrystalDiskMark 4K testing does literally the exact same stuff I'm trying to do though

And there you go; disabling my antivirus and the speeds jump up to 400MB/s.

edit: actually seems like the problem was fixed since with my antivirus enabled the speeds were still ok

[JoostinOnline]

1 minute ago, NunoLava1998 said:

CrystalDiskMark 4K testing does literally the exact same stuff I'm trying to do though

No it doesn't. It simulates it. And not all that well. Caching systems can essentially trick it into giving higher speeds.

[NunoLava1998]

1 minute ago, JoostinOnline said:

No it doesn't. It simulates it. And not all that well. Caching systems can essentially trick it into giving higher speeds.

Pretty sure my SSD doesn't have cache iirc; still though it seems to be magically fixed

[JoostinOnline]

3 minutes ago, NunoLava1998 said:

Pretty sure my SSD doesn't have cache iirc; still though it seems to be magically fixed

Every modern SSD has a cache, and you have Optane cache too.

[NunoLava1998]

1 minute ago, JoostinOnline said:

Every modern SSD has a cache, and you have Optane cache too.

Makes sense then. Seems to be magically fixed lol

[JoostinOnline]

Just now, NunoLava1998 said:

Makes sense then. Seems to be magically fixed lol

The files you were copying are probably cached now.

[NunoLava1998]

1 hour ago, JoostinOnline said:

The files you were copying are probably cached now.

I can do a 16GB test with crystaldiskmark (which should BTFO cache) and the 4K speeds are the same