Solved Mechanical Hard disk Performance

Pocah · Jul 6, 2023

I have two PC's, identical, running Win 11 Pro 22H2. They both have an 8TB mechanical hard drive which is half full.

I started to notice something strange, recently, that the write performance is terrible. Copying data to either drive, they will (seemingly randomly) slow right down at, oh, about ten second intervals. It is random, though, so it might happen right away. Anyway, the write speed may fall to zero bytes per second. And worst case, it may sit at zero for five seconds before it starts to recover. It may well make a full recovery, but then it will fall away again.

This is copying 31 large files to the drive. After I took the snapshot, the speed actually fell to 0 and stayed there for some time.

Reading the same files, there is no problem.

Can anyone suggest anything here? Maybe some other tests?

jvickers · Jul 6, 2023

It would probably help to have the drive manufacturer and other drive stats.

Pocah · Jul 6, 2023

jvickers said:
It would probably help to have the drive manufacturer and other drive stats.

WD RED Plus 8TB. They are the recent CMR drives.

I am not sure whether this is normal behaviour for Windows 11 mechanical drives. Perhaps what I am looking at is the cache filling up or something, I don't know.

WAI · Jul 6, 2023

Yeah the ~~brand~~ to the cache amount would help but having the drives half full as you say could slow things down for sure

Reading ofc no issues but reading and knowing your drives half full is the problem no doubt

jvickers · Jul 6, 2023

Same age, same cable rating, everything identical?

WAI · Jul 6, 2023

jvickers said:
Same age, same cable rating, everything identical?

That wouldn't matter from my knowledge. Again it's the fact you're drives are half full or whatever

Writing at 5MB though is like a USB2.0 Speed

Pocah · Jul 6, 2023

jvickers said:
Same age, same cable rating, everything identical?

Yes.
I can't tell you what the initial write speed was. Unfortunately, when they were first set up there was about 3TB written to both of them but this was over a network, so very slow. It was only recently that I noticed there was an issue when I copied some files from an internal SSD.
The 31 files, by the way, are a total of 8GB.

jvickers · Jul 6, 2023

Pocah said:
Yes.
I can't tell you what the initial write speed was. Unfortunately, when they were first set up there was about 3TB written to both of them but this was over a network, so very slow. It was only recently that I noticed there was an issue when I copied some files from an internal SSD.
The 31 files, by the way, are a total of 8GB.

You might want to run a health check on both.

Settings -> Storage -> Advanced storage settings -> Disks & volumes
Look at the properties of each. It could be one drive was used more than the other and isn't as healthy.

I'm sure you'll get some other advice that might prove to be a more fruitful road to investigate.

Pocah · Jul 6, 2023

Here is the same copy on the other PC.

It's remarkably different. The transfer rate starts well. 500MBps. Then suddenly drops to zero. Then recovers to about 250MBps, then zero again. Rinse, repeat.

Pocah · Jul 6, 2023

Oh actually, I just re-ran the same test on the first PC and got a similar result.

The speed is a little lower, but they then have different CPU's. But you can see, roughly the same thing as the post above.

I am assuming here that I am hitting the cache limit. I'm not exactly sure what was wrong with that first graph, but I can't reproduce it now.

jvickers · Jul 6, 2023

Pocah said:
Here is the same copy on the other PC.
View attachment 64133
It's remarkably different. The transfer rate starts well. 500MBps. Then suddenly drops to zero. Then recovers to about 250MBps, then zero again. Rinse, repeat.

Pocah said:
Oh actually, I just re-ran the same test on the first PC and got a similar result.

View attachment 64135
The speed is a little lower, but they then have different CPU's. But you can see, roughly the same thing as the post above.

I am assuming here that I am hitting the cache limit. I'm not exactly sure what was wrong with that first graph, but I can't reproduce it now.

Oh, you're dealing with two different PCs. Yes, the hardware differences could come into play.

Pocah · Jul 6, 2023

jvickers said:
Oh, you're dealing with two different PCs. Yes, the hardware differences could come into play.

Well, they are identical in every way, apart from the CPU. One is a 9700K the other is a 9500T. The T is obviously a little slower. I think that one peaked at a little less than 400MBps whereas the other at over 500MBps.

reece · Jul 6, 2023

as your using a HDD - does the drive need defragging? although might take time to defrag. my 2 cents

ian50 · Jul 7, 2023

@Pocah

Yes, I put up a similar post here about 6 weeks or so ago.

I was testing Win7 vs Win11 on speed of copy of large (>2Gb) files from the C:\ to an external USB3 spinner.

Same files for copy, same external disk, both PC's with the same amount of RAM (16Gb) - one PC on Win7 and the other on Win11 22H2 22621.xxxx. The Win7 PC has an i5-8265U CPU while the Win11 PC has an i5-10210U.

The Win7 standard copy was consistently significantly faster by some 20% or so. I repeated this quite a few times and always had similar results. The Win11 copy would stutter to a random halt, just as you've experienced.

My tentative hypothesis is that the Win11 RAM caches are not nearly as well managed by that OS as those in Win7. As far as I can tell, MS knows this and has done its' predictable crab-walk by insisting that this issue does not affect the majority of "home" users.

I've managed this to a degree by forming Win11 RoboCopy batch files for the copy functions most used. This has eased the situation to a degree.

Pocah · Jul 9, 2023

ian50 said:
@Pocah

Yes, I put up a similar post here about 6 weeks or so ago.

I was testing Win7 vs Win11 on speed of copy of large (>2Gb) files from the C:\ to an external USB3 spinner.

Same files for copy, same external disk, both PC's with the same amount of RAM (16Gb) - one PC on Win7 and the other on Win11 22H2 22621.xxxx. The Win7 PC has an i5-8265U CPU while the Win11 PC has an i5-10210U.

The Win7 standard copy was consistently significantly faster by some 20% or so. I repeated this quite a few times and always had similar results. The Win11 copy would stutter to a random halt, just as you've experienced.

My tentative hypothesis is that the Win11 RAM caches are not nearly as well managed by that OS as those in Win7. As far as I can tell, MS knows this and has done its' predictable crab-walk by insisting that this issue does not affect the majority of "home" users.

I've managed this to a degree by forming Win11 RoboCopy batch files for the copy functions most used. This has eased the situation to a degree.

Yes, seems something like that. If I copy data to it a little slower, then everything works just fine. It definitely seems to be hitting some cache limit or other. I've given up "solving" it now, content that it's not a hardware fault.

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