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Fix disk staying idle 0%

2018/08/07 15:12

When there is load on server disk for read/write IO, the disk tend to show 0% disk idle momentarily. This means that the disk has high IO operation being done.

However, if the disk idle % stays at 0% for long time then it will cause client to lag and even freeze for few seconds.

So, how to fix this issue:

1. If you currently use HDD as writeback change it to SSD. Using SSD as writeback disk is better than harddisk as SSD has good IOPS.

2. If you have more that 15-20 clients use two or more SSD for writeback disk 

3. Sometime the SSD used do not have good read/write speed (less than 200MBps), if that's the case for you then upgrade your SSD to better one. We recommend using Samsung Evo SSD as they have reliable performance.

4. Make sure your disk are all formatted to 32K allocation unit.

5. Set 2048 MB RAM Cache for all of your writeback disks, There is no need to set any higher. If your server has less RAM, then you can set 1024MB RAM Cache for writeback disks.

6. If after going through the above, if your disk idle % still stays at 0% for long period, then you need reinstall your OS. We recommend using Windows Server 2008 R2 or Windows Server 2012 R2.

7. If you have installed antivirus application or other system scanning tool that scan the computer when it idle, then you should remove/disable it. As it will scan all disk causing it to be idle 0%.

8. For writeback disk, your clients may have idle time disk defragementation scheduled and running when pc becomes idle. 
To fix this, you need to do the delete the scheduled task in client PC in super client mode.

a. Run Command Prompt as administrator 

b. Run the command :-  schtasks /Delete /TN "\Microsoft\Windows\Defrag\ScheduledDefrag" /F

This will delete the defragmentation schedule and help elevate the writeback idle issue


a. Sometime if the cable of the disk are not connected securely, your disk will seem like it has disappeared (as in it will not show on server). It this happens, please change the sata cable connected to the disk

b. Check your disk temperature, if SSD get too hot its performance will drop significantly. So if your SSD are hot then cool them using cooling fans.

c. Check your SSD health, if your SSD has been in used for some time then its wear level will have increased. Any SSD with 30-40 % wear level will not function well for writeback disk.


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