Hard Disk Monitoring

Usually hard disks require highest power when they spin up.

Constant and frequent spin-up / spin-down cycles not only causes higher power consumption due to the intensive power requirement for spin up, but can also wear mechanical components: both the motor, bearing - and also the read/write heads due to constant parking.
This is usually why manufacturers provide a maximum start/stop count (and/or maximum head load/unload count).

And also we can mention the "stress" caused for the power supply by the high current on startup.
This is not a big factor for internal 3.5" hard disks (except if you have many of them), but if you use 2.5" portable hard disks (powered from USB line) then this may cause high stress for motherboards due to higher current on the 5V line. For example, using 2-3 such external 2.5" USB hard disks, the frequent spin-up / spin-down can kill the motherboard quickly.

And yes, as you wrote, spin down reduces hard disk performance / usability, as then we need to wait for the hard disk to spin up again and be ready. We need to mention that some systems (eg. hard disk controllers, drivers, OSes) may not tolerate well if they need to wait, for example if the hard disk can't spin up so quickly - and can even disconnect / remove the hard disk from the system.
This happens relatively often with older external hard disks (which may require more time to spin up compared to their new state).

Because of the above, personally I always recommend to leave the hard disks spinning. The benefit of the reduced power consumption (if there is any) is much less than the stress / lifetime degradation of all components in your system (including, but not limited to the hard disk, as this includes the power supply, motherboard, etc.)

> You can save energy by letting the disks spin down.
> If they are 7200rpm disks they will use 6-9W when idling, or 0.5W when spinned down.


These values may be true for very old hard disks.

Let's check a really high capacity hard disk - a 6 TB drive:

http://www.hdsentinel.com/storageinfo_d ... 20WD60EFRX

As you can see, even during seek, it's power consumption is only 5.3 W, but when it is idle (just spinning, without seek / read / write), the power requirement is 3.4 W.


Or we can see a green drive with less heads/disks (eg. 1 TB), just to compare the generic difference:

http://www.hdsentinel.com/storageinfo_d ... 20WD10EARX

As we can expect, the numbers are slightly lower: 4.9 W during operation (seek), 2.8 W in idle - and 0.4 W when spin down.


For 2.5" hard disks (even with higher capacities) the difference is much less, usually around 1 - 1.5 W

So generally if you allow hard disks to spin down, you can save 1-3 W only.

The constant spin up / spin down cycles may eliminate this completely - and the wear / lifetime degradation will result in lower lifespan of the hard disk and also other components.

For people want to save power, I can recommend to consider using simpler CPUs and/or VGA cards.
As they can very easily use 80-100 W power (or even more), they use far more power than any hard disk.

> The best would be to let a drive running all the time with good cooling
> best lifetime with HDD would be in a vibration-less environment where it is running with a constant temperature on all sides of the HDD.

Yes, this is absolutely true. High temperature, vibration / mechanical shock are the most common causes of hard disk problems.
Also I'd mention good cables, connections and stable power supply to provide power for operation.

hdsentinel wrote: Also if Hard Disk Sentinel detects that the hard disk drive is sleeping (if that provided by the hard disk controller/motherboard driver properly) then it does not wake up the drive just to detect and update hard disk status.

It is not true at the midnight. On time 0:00 HDS wakes up drives, even if sleeping status is displayed.
Is it intended functionality?

Yes. At midnight, Hard Disk Sentinel clears all daily counters (eg. daily reads / writes / temperatures etc.) and start a new day with "fresh" information detected. That's why then it always detect new information about all hard disks.

That is a very bad idea. At midnight I am trying to fall asleep... (yes, some drives can generate a lot of noise)
Hard Disk Sentinel should not wake up drives in any case.

Thanks, I see.
But if this is not performed, the statistics would be not accurate.

Maybe it is possible to add option (for example) to completely prevent detections between 22.00 - 8.00, but this may cause that some displayed average / daily statistics may not be accurate.

Let the user decide whether HDS can wake up drives for detections and at what time.

Thanks for your suggestion.
Will need to consider this to make sure that the accuracy of the reported information should not decrease, so I can't promise this soon, but maybe available in a later version.

Another consideration is heat because heat is the enemy of electrical and mechanical systems. Leaving drives running all the time generates heat which not only stresses themselves but also their environment. Many external hard drives in particular have very poor cooling and tend to run hot. These are also frequently used for backup, which does not require them to be online all of the time, so to keep the constantly spinning is not a good idea. Besides, many hard drives are rated for 100's of 1000's of spin up/down cycles. Because of all this I have HDSentinel set to monitor my disks every 12 hours, which is the maximum. While I won't get notified of any suddenly impending disasters I should hopefully be notified of more slowly developing problems... which is usually the case in my experience.

BTW one thing that is missing from the web report is the time the readings were taken.

Hi Zimberto,

Thanks for your message and the information !

To keep drives sleeping, you may consider using the new function in 4.71.10 version released some days ago:
select Configuration -> Advanced options -> Automatic detection based on disk utilization.

This way when the periodic detection should happen (based on the configured detection frequency) Hard Disk Sentinel checks not only the power state of the drive (which may be mis-leading / incorrect) but also verifies if there was disk activity since last status detection and attempt detection only if so.


> BTW one thing that is missing from the web report is the time the readings were taken.

The report contains the report creation date/time, listed on the top.

hdsentinel wrote:> BTW one thing that is missing from the web report is the time the readings were taken.

The report contains the report creation date/time, listed on the top.

That's the time the report was created... i.e. current time. It's not the time the readings were taken... unless I'm incorrect.

Yes, you are correct and I agree: if the detection frequency is set to low, there may be long time (eg. hours) passed since last status update, it may be interesting to check from the report when the actual status update and reading done, so yes, it may be added to the report as well.
Thanks for the tip !

ron wrote:Even worse, just like every other program I've tried that monitors SMART data, this one keeps all drives spinning 24/7 - very undesirable.

I set the hard drive spin down time in Windows to 5 minutes.

I listened as a few minutes later the external drive spun down.

I removed the external drive from the HDS main window. The hope here was that for drives HDS did not work well with I could tell it to COMPLETELY ignore them.

But, precisely at the 30 minute interval I had defined, the external drive spun back up. Checking the graph confirmed that HDS caused this.

This was the excess things which are not taking place towards those efforts