[SOLVED] Cristaslmark shows over 100 MS/s but transfer under 30 MB/s

[funkytwig]

Can't figure this. I get really good results from my external USB WD black games drive but when I transfer files I get very slow rates. What's going on?

 

[USAFRet]

Can't figure this. I get really good results from my external USB WD black games drive but when I transfer files I get very slow rates. What's going on?

Transferring a lot of small files is significantly slower than the sequential result in CDM.
That's the way it works.

 

[funkytwig]

OK, so I run CristalDiskMark on an HD and got

Looks good but then I wondered, what does it all actually mean. SQL=Sequential, RND=Randon. 1M/4K, that all fairly obvious. But what gives with the second line. Q & T. I could hazard a guess Q is something to do with Queuing, exactly what Q means eludes me. And then the elusive T, the time maybe. It's all a bit of a mystery to me (and the internet in general, I did a bunch of googling). Some posts get close, Seems the best but no one seems to know for sure.

Can someone please enlighten me?

Yours confused,
Ben

 

[funkytwig]

Transferring a lot of small files is significantly slower than the sequential result in CDM.
That's the way it works.

Indeed, I get that, but what does it all actually mean. I'm amazed they don't have any full docs explaining this.

 

[USAFRet]

Indeed, I get that, but what does it all actually mean. I'm amazed they don't have any full docs explaining this.

The CDM Sequential is one single block of data.

Copying your hundreds/thousands of small files, the system has to literally stop, consult the File Allocation Table, and locate the next file. Parts of which may be scattered all over the physical platter.

This is MUCH more evident on a spinning hard drive. The head has to move to the proper place, and then wait for the platter to spin around. Repeat repeat repeat a few hundred thousand times.

A single file of 10GB will transfer a lot faster than 1,000 small files, totaling 10GB.

 

[USAFRet]

Like this:
You have 10 books. You wish to carry them to the neighbors house.

All 10 books in one box, you make one trip.

Those same 10 books, disassembled and individual pages all over the house.
You have a document telling you exactly where every page is.
You can only carry one page at a time to the neighbors house. And then reassemble the books in the proper order.

 

[funkytwig]

OK, but we digress. Understanding what all the numbers mean is nice but my big issue is copy speeds on my Laptop are abysmal even although Crystalmark says they should be excellent.

 

[USAFRet]

OK, but we digress. Understanding what all the numbers mean is nice but my big issue is copy speeds on my Laptop are abysmal even although Crystalmark says they should be excellent.

And again, it depends on the number of files, their individual sizes, defrag level of the HDDs, performance of the drives involved, etc, etc.

The sequential number from CDM is a best case test, NOT what is typical in copying files.

 

[funkytwig]

And again, it depends on the number of files, their individual sizes, defrag level of the HDDs, performance of the drives involved, etc, etc.

The sequential number from CDM is a best case test, NOT what is typical in copying files.

Indeed but my HD is really slow/crap when used and fairly fast when tested. something seems amiss. It feels like I have not got Best Performance checked on one of the drives and I have it checked for both. Or there is something wrong with my machine or one of the HDs.

 

[funkytwig]

OK, nailed it. It was the disk I was copying from that is VERY slow.

 

[USAFRet]

OK, nailed it. It was the disk I was copying from that is VERY slow.

Yep.
The slowest device in the chain dictates performance.

You could be copy/paste from the fastest PCIe 4.0 SSD in the world.
Talking to a very very slow old HDD....the HDD is what dictates.