Would replacing the disk drives the only option or does someone have another idea what's going on here and how to fix/ mitigate it?
Maybe first power down the NAS, and swap drive 1,2 and 3,4 (moving the inner drives to the outer slots). Then do a defrag and see if the heating problem stays with the slots, or moves with the drives. After that test, I'd power down the NAS and restore the drives to their original positions.
I would certainly consider replacing the drives. Enterprise-class (in my opinion) are overkill for the RN100 - it is limited by it's processor speed, not the disks. I suggest starting over - two WD30EFRX or two ST3000VN007 would cost a total of about $200 (current US prices) and would give you the same capacity you are using now. Then you'd have two slots for expansion (and if you like, you can put the drives in bay 1 and bay 4 to create more distance between then).
Avoid WD EFAX models between 2 TB and 6 TB - they are SMR technology, which IMO aren't great choices for RAID. The older EFRX line is fine. Ironwolf drives are also a good option. BTW, many desktop models are also not SMR, so I won't use them either.
Hello StephenB,
many thanks for your response. I already moved the inner drives to the outer slots and vice versa. The RN104 came up fine in this configuration.
I'm using this type of enterprise drives because I received a bunch of them for free. Nevertheless, I'm thinking about replacing them. Thanks for providing recommendations. Besides this, I now left the front door open although I do not believe it will help. The outside air temperature is always about 15°C all the year and except the front door, nothing is blocking the air flow.
I believe in an internal disk drive cooling issue when they slow down after defrag completed. I don't know if they slow down their platter rotation speed and this is than reducing their cooling ... doesn't matter anymore. I turned off defrag already.
I logged in to the NAS using ssh and run smartctl. The values returned by smartctl matched the temperature of the disk drives shown in the performance window of the GUI. Seems to be the disk drives are reporting their temperature accurate.
I attached a text file including the complete smartctl output ... just in case someone can see more than I do.
The test confirms that this is not a fan problem but the temperature of the disk drives really goes up immediately after defrag completes - why ever.
Since both the ReadyNASOS and smartctl rely on the drive reporting it's own temperature (and the OS probably calls smartctl for that), this only indicates the reported temperature is consistent, not correct. But with more than one drive reporting a similar temperature, it likely is correct.
It sounds like an airflow problem, but with the NAS out on your desk, there shouldn't be anything external contributing to that. The ambient air temperature is within normal comfort range, correct?
Does the fan speed initially drop at the conclusion of the defrag and then have to jump up when the temperature starts to increase? I've seen the hystereses and step sizes of the fan control to be less than optimal on legacy NASes, but I don't have a lot of newer ones (and no 104) to evaluate them for those cases. It may be that the greater amount of heat produced by the enterprise drives is outside the expectations Netgear had when establishing the fan control parameters for a 104. But I've run 2TB and 3TB drives from the same family in both 2 and 4 bay legacy NASes running OS6.x and had no issues with high-intensity processes like initial sync or scrub (I don't use defrag, I think it's mostly a waste of time on RAID and it can quickly increase the space used by snapshots).
Hello Sandshark,
many thanks for your response, too. I assume the temperature is correct as the drives are really warm/ hot.
The temperature at my desk is about 24°C, in the cellar room, where the RN104 is usually located, the temperature is about 15°C all the year.
When defrag is complete, the fan speed did not go down. It started to increase immediately, first slowly, than in larger steps. It's for sure not the fan ... it is a new one providing more air pressure than the original one. See my response to StephenB, too, please.
The issue is only occuring when running defrag and defrag completed. No issues at all running data scrubbing or disk test.
We can stop here ... I'll think about how to "resolve" this issue.
@Sandshark wrote: But I've run 2TB and 3TB drives from the same family in both 2 and 4 bay legacy NASes running OS6.x and had no issues with high-intensity processes like initial sync or scrub (I don't use defrag, I think it's mostly a waste of time on RAID and it can quickly increase the space used by snapshots).
Still, it is weird that this happens repeatedly after a defrag. It does make me wonder if there is something off with the file system.
Another thing that @HolgerGT86 could try is doing a factory reset, rebuild the NAS, and then reload the data from backup. The risk here is that the disks might overheat during the RAID sync. But the fact that they don't overheat during a scrub suggests that they won't.
I'll think about starting over from scratch and restore a backup. I'm not sure though how to reload all data from backup including the user access rights and share settings as I'm backing up the RN104 to 2 USB drives attached to it. Besides this the RN104 is used to store Mac time machine backups and Windows 10 backups. I'm afraid to lose/ break things, so I'll delay this activity to the autumn/ winter time.
Many thanks for all you support/ help. You may close this thread.
