Question Very slow read speed. Normal write speed.

Oct 26, 2021
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Hi everyone!
I'm experiencing this issue. Suddenly my 3TB HDD is mostly unusable. From Crystal Disk info the HDD seems in "good" condition. It doesn't make any strange sound. From Crystal Disk Mark the write speed is around 80MB/s, while the read speed is around 3MB/s. Gaming is impossible because loading screens are eternal and sometimes the game even fails to load textures or entire parts of the map. Moving files too, of course. Any clue?
I'm doing a Defragmentation at the moment, never done one before, so the problem may be it! I will update this thread. Hope someone can help me, thanks!
 

Aeacus

Glorious
Ambassador
I'm doing a Defragmentation at the moment, never done one before, so the problem may be it!
Yes, it may be.

For HDDs, doing defrag once a month is good. It keeps everything in order and at reasonable speeds, especially when HDD is OS drive and/or gets a lot of files written/deleted to it.

However, even after the defrag and drive is still slow, then it is indication of dying drive. At this point, i'd back up all the data and buy a new drive (or vice-versa) before drive completely dies.

Also, how full the drive is?

Rule of thumb, regarding free space to keep, at all times, on a drive, is 20% of max capacity.
So, for 3TB drive, keep at least 600GB free. At bare minimum keep 10% free (300GB).
 
Oct 26, 2021
6
1
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Yes, it may be.

For HDDs, doing defrag once a month is good. It keeps everything in order and at reasonable speeds, especially when HDD is OS drive and/or gets a lot of files written/deleted to it.

However, even after the defrag and drive is still slow, then it is indication of dying drive. At this point, i'd back up all the data and buy a new drive (or vice-versa) before drive completely dies.

Also, how full the drive is?

Rule of thumb, regarding free space to keep, at all times, on a drive, is 20% of max capacity.
So, for 3TB drive, keep at least 600GB free. At bare minimum keep 10% free (300GB).
Thanks for replying. The free space is around 350GB at the moment, but I sincerely doubt that could be the problem. Anyway I will delete some files in order too free some space of course!

I would like to know what can I do on a "software side" before starting swaping cable, or mobo, or HDD and so on...?
 

Aeacus

Glorious
Ambassador
but I sincerely doubt that could be the problem.
If your HDD is OS drive, then do note that OS needs free space to write temp files. Also, pagefile.sys size varies and it can become quite large.

I would like to know what can I do on a "software side" before starting swaping cable, or mobo, or HDD and so on...?
IF the drive is dying and you need to replace it, while recovering data from it, best course of action would be not to use that drive before you're ready for recovery. Since every following usage shortens the lifespan of the drive, up to a point, where you can't access ANY data on it. Also, writing on dying drive is bad and only accelerates the death of a drive.

When i suspect drive dying:
  1. power off system
  2. disconnect dying drive (SATA data and power)
  3. when new drive is ready
  4. connect both drives to PC (when PC is turned off of course)
  5. copy/paste all needed data from dying drive to new drive
  6. after recovery, power down and disconnect dying drive
  7. keep the dying drive or scrap it, your choice
Now, when dying drive is OS drive;
3.1 connect only new drive
3.2 install OS + drivers
4.1 connect dying drive for data recovery
5.1 copy/paste personal data (games, programs etc are best installed fresh to a new drive)
 
Oct 26, 2021
6
1
15
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If your HDD is OS drive, then do note that OS needs free space to write temp files. Also, pagefile.sys size varies and it can become quite large.



IF the drive is dying and you need to replace it, while recovering data from it, best course of action would be not to use that drive before you're ready for recovery. Since every following usage shortens the lifespan of the drive, up to a point, where you can't access ANY data on it. Also, writing on dying drive is bad and only accelerates the death of a drive.

When i suspect drive dying:
  1. power off system
  2. disconnect dying drive (SATA data and power)
  3. when new drive is ready
  4. connect both drives to PC (when PC is turned off of course)
  5. copy/paste all needed data from dying drive to new drive
  6. after recovery, power down and disconnect dying drive
  7. keep the dying drive or scrap it, your choice
Now, when dying drive is OS drive;
3.1 connect only new drive
3.2 install OS + drivers
4.1 connect dying drive for data recovery
5.1 copy/paste personal data (games, programs etc are best installed fresh to a new drive)
No, it is not the OS drive, luckly. Anyway, I have many drives so I'm already trying to do a Backup on another one, although it is REALLY slow.
 
Oct 26, 2021
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I guess defrag didn't help much?

Yeah, it is slow when drive is dying. Cross your fingers that you can get all the needed data off from it, before it dies.

Btw, you may run into corrupted files, that you can't copy/paste over, since source drive at those sectors is already gone for Win to read them.
Defrag is not over yet.

Anyway, I don't feel like it is dying to be honest. I'm able to explore the drive freely and I can open every file I wan... It is just incredibly slow. Furthermore, writing speed is completely fine. I don't know, I'm probably wrong.
 

Aeacus

Glorious
Ambassador
Defrag is not over yet.
Best to let defrag finish, before you do anything else on the drive.

I had one HDD die on me. WD Blue 500GB.
At 1st, when drive was new, defrag took as little as 15 mins. Over time, defrag time started to increase slowly, up to 30 mins for ~78% full drive. One day, i noticed very high CPU usage in the "Hardware interrupts and DPCs". I suspected my 500 GB drive and did defrag on it at once. Defrag took 15 hours!. And i'm not kidding here.
At that point, i knew drive was dying, so, copy/pasted everything from it and after that, made deep format. Funny thing is, drive was about 11 months old at that point. So, i went and put in warranty claim (it came with 2 years of warranty). Store, from where i bought it, took the drive in and sent it to service. 2 weeks later, i got the call from the store to come and pick up brand new WD 500 GB drive, since my old drive was dead. So, went and collected a new drive.
Sadly, new WD 500 GB drive started to show same symptoms after about 1 year of use. So, i disconnected the drive and put it into the unused hardware pile i have at my home. Not going to bother with warranty claim again. Instead, learned not to buy WD Blue 500 GB drive again.
Though, i have several WD Blue 1TB drives and those are solid as rock. 5+ years in service and still going strong.

Oh, i use MyDefrag for my HDDs,
link: http://www.mydefrag.net/

But i'm also in the process of phasing out all HDDs in my PCs. Have new SSDs bought but i'm quite busy and haven't had time to install them yet.
 
Last edited:
Oct 26, 2021
6
1
15
0
Best to let defrag finish, before you do anything else on the drive.

I had one HDD die on me. WD Blue 500GB.
At 1st, when drive was new, defrag took as little as 15 mins. Over time, defrag time started to increase slowly, up to 30 mins for ~78% full drive. One day, i noticed very high CPU usage in the "Hardware interrupts and DPCs". I suspected my 500 GB drive and did defrag on it at once. Defrag took 15 hours!. And i'm not kidding here.
At that point, i knew drive was dying, so, copy/pasted everything from it and after that, made deep format. Funny thing is, drive was about 11 months old at that point. So, i went and put in warranty claim (it came with 2 years of warranty). Store, from where i bought it, took the drive in and sent it to service. 2 weeks later, i got the call from the store to come and pick up brand new WD 500 GB drive, since my old drive was dead. So, went and collected a new drive.
Sadly, new WD 500 GB drive started to show same symptoms after about 1 year of use. So, i disconnected the drive and put it into the unused hardware pile i have at my home. Not going to bother with warranty claim again. Instead, learned not to buy WD Blue 500 GB drive again.
Though, i have several WD Blue 1TB drives and those are solid as rock. 5+ years in service and still going strong.

Oh, i use MyDefrag for my HDDs,
link: http://www.mydefrag.net/

But i'm also in the process of phasing out all HDDs in my PCs. Have new SSDs bought but i'm quite busy and haven't had time to install them yet.
Hello!
After defrag, write speed is almost doubled(!!) but read speed has remained the same, around 3MB/s... I don't know, it's weird...
 

Aeacus

Glorious
Ambassador
Oct 26, 2021
6
1
15
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Looked around and found another person with similar issue, where her HDD has the same, slow read - fast write issue,
link: https://forums.tomshardware.com/threads/extremely-slow-hdd-read-speed-whole-write-speeds-are-fine.3552863/

From that topic, comes other things to try:
  • plug your HDD into different SATA port on your MoBo.
  • look if not HDD indexing isn't currently in process.
If it fixes it. All is good. If not, most likely, the HDD is the issue.
Yep, I already solved the problem. It was the cable!
Thank you very much anyway, you've been very kind and helpful!
 
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