Solved SSD overheating during btrfs data scrubbing

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Solved SSD overheating during btrfs data scrubbing

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Today my ds620 switched off after I started the manual datascrubbing.
The pool 2 that was scrubbed consists of two 1.8TB SSD in SHR formatted in BTRFS.

the system shut down with the warning that disk 3 reached 61 degr C.
Scrubbing was at about 15%, 61 degrees is reached in just a few minutes. It is reproducible.

the thing I do not understand: mirror disk 4 is right next to disk 3, same disk, same model, same age, remains at 41 degrees, while disk 3 temp raises 20; degrees in just a few minutes. Why this difference?

the SHR in pool 1 consists of 3 ssd (3* 480 GB) and no issues there.
 
1. what exact SSD, include PN?
2. common SSD operation temperature is rated between 0ºC and 70ºC, then 61 is in range. But needs to know exact disk details.
3. It’s quite normal for an SSD to jump really quickly to high temp in seconds. Specially when the SSD doing a heavy job as the Data Scrubbing is.
4. Most SSDs implement thermal throttling as a safety feature if a drive gets too hot =
drive will start slowing down to prevent itself from failing. What is many times seen in bad SSD performance. Then slow performance = longer time for the scrubbing = long heavy load = higher temperature.

Scrubbing in SW RAID1:
SW controller chooses which disk will be searched for a data discrepancies, then one of the disk must be hotter than another.
 
as was written, follow this disk vendor spec:
Operating temp: 0°C~70°C

is the overheating observable during another services than Data Scrubbing?
Are you sure, that the NAS switch-off has been performed by the overheating control?
Do you have a logs?

For a preventing such cases (when the overheating shutdown is confirmed) you can manually change (up t your own responsibility) a threshold of the overheating temperature check for auto shut down by DSM:
/usr/syno/etc.defaults/scemd.xml
 
The reason was indeed in the synology log.
never had the temperature issues before.
thanks for the information, what I will do is add extra cooling when scrubbing, and leave default setup as is.
 
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Thanks for the input, data scrubbing on a pool is indeed done disk by disk. The SSD disk 4 made the system shutdown a bit later, when I manually stopped scrubbing on disk 3.
So your comments is confirmed. It is clear that data scrubbing on this SSD type can only be done with more airflow than “low”. External cooling is needed as even full fan speed is not sufficient. Case clear and can be closed.
 
I'd like to come back to the topic after contact with Synology support, although the issue has been solved (by tweaking the suggested settings file).

Basically there are two things:
1) My SSD are not on the compatibility list, and support is not able to help.
2) The temperature limit settings on the drives are (in my humble view) too low, and do not reflect the higher temperatures that SSD typically reach during peak loads like scrubbing. I think that is a design flaw for a NAS like the DS620Slim that is meant to work with SSD.

Support claims that modification of the file, is not supported as it is meant to protect certain parts on the DS620 mainboard.
My response was, that if the main board temp is critical, they should put a temp sensor there, and not look at SSD Temperature (the SSD next to the one that is scrubbing was only 35 degrees, so how warm can the Main board be?).
Finally they indicated they would pass my remark to development. Who knows there will be a solution...

And finally, Now I understand why the DS620Slim does make more noise than my DS415+; it just over-cools my system. Better not to buy Silent SSD as the fan ruins it...
 
... reason, why you can get better advice here than in official support

re SSD and temperature:
- SSD is quite hot than HDD, because physics
- then you need more airflow
- when you don’t have AC in the room or in rack, you need more airflow
# more airflow = more noise

... finally, NAS isn’t device for a living room or sleeping room operation environment. NAS need airflow from basics point of view, otherwise it will change to grill. This is really problem, that people use NAS in the living spaces, then they will expect that the NAS must be silent. This is bigger mistake of such NAS owners. And no one from vendors or sellers don’t explain them this principle. No one.
 
For sure the advice here is much better!
I sort of agree with your remark on temperature. For cooling, the generated wattage is more important than the temperature. A 70 degrees sATa SSD may well need less airflow than a 50 degr 7200RPM HDD. I have to test, but I think the outgoing air temperature on the SSD machine will be lower than on DS415+, even though the disk temp of ssd is much higher, just because less power has to be removed.

Noise is not an issue here fortunately as the system is far away, it was just the observation that fan speed is higher, and in my view not needed.
 
... finally, NAS isn’t device for a living room or sleeping room operation environment. NAS need airflow from basics point of view, otherwise it will change to grill. This is really problem, that people use NAS in the living spaces, then they will expect that the NAS must be silent. This is bigger mistake of such NAS owners. And no one from vendors or sellers don’t explain them this principle. No one.
Are you saying that my DS218+ should not be in my bedroom in my New York City Apartment? When you live in New York City, you can't afford a second home, LOL, so I am stuck here. Is there anything I need to do to keep my NAS cool? Right now one of the hard disk is 100 degrees Farenheit and the other is 104F. Is that bad?
 
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Is that bad?
I wouldn't worry about it that much. I have about the same temperatures in my NAS devices that are inside a 42 unit rack in the basement.

True, those are part of a 12bay unit and they are enterprise-grade 7200 RPM drives running at about 100-102F. In the same rack, there is also a 2 bay 718+ model running all SSDs and they are at about 88-89F. So just to give you the idea that your drives are not running nearly as hot as you think all things considered. Spindel drives will be hotter then ssds ofc, but unless your nas is inside a shoebox in a closet, you will be fine.

Finally, one of my 4bay nas running 4x4TB HDDs in my office on the top floor (so not inside a rack, yet) has temperatures from about 93-95F on average. Now, this wouldn't be much of a change even if I move it to the rack right now because the basement is actually less hot then my office. This just gives you the idea of how a different size and type of drive can have on the temperature side of things.

Again, taking all things considered, 100F+/- is fine. Less is better ofc, but not everyone has room for putting the NAS in an ideal space.
 
For cooling, the generated wattage is more important than the temperature. A 70 degrees sATa SSD may well need less airflow than a 50 degr 7200RPM HDD. I have to test, but I think the outgoing air temperature on the SSD machine will be lower than on DS415+, even though the disk temp of ssd is much higher, just because less power has to be removed.

Residual heat produced by SSD and HDD is still residual heat.
What isn’t same is the operation temperature condition, there is 20C difference (better) for the SSD = means max temperature for “normal” operation.
When you need take out same residual heat from same box you need same energy for such job.
But,
1. HDD has a metallic body, even with larger surface than SSD. And iron body has better thermal admittance than SSD body. Then you need less energy for same operation temperature keeping.
2. Why to keep same operation temperature for the HDD or SSD in NAS? Because thermal airflow from the disks in the NAS is affecting PCB NAS parts, where as we know is just passive cooling (CPU, RAM,...).

as you can see it’s not so easy from the airflow point of you. You need to keep equilibrium for all parts in the NAS for the max. possible lifespan or your expected period.
 
as @Rusty wrote 100F is really good
then it’s up to your apartment conditions and NAS service model (more jobs = more temperature), or special jobs with impact to the disk drives temperature (e.g. scrubbing).
My post was about scenario when someone puts the NAS into enclosed cabinet with minimal airflow, because he doesn’t like noise from spindles or air vents. Then their NAS or disk drives lifespan is degraded.
People (some also here) claim the noise from NAS. But noise is the base of normal storage operation.
 
I wouldn't worry about it that much. I have about the same temperatures in my NAS devices that are inside a 42 unit rack in the basement.

True, those are part of a 12bay unit and they are enterprise-grade 7200 RPM drives running at about 100-102F. In the same rack, there is also a 2 bay 718+ model running all SSDs and they are at about 88-89F. So just to give you the idea that your drives are not running nearly as hot as you think all things considered. Spindel drives will be hotter then ssds ofc, but unless your nas is inside a shoebox in a closet, you will be fine.

Finally, one of my 4bay nas running 4x4TB HDDs in my office on the top floor (so not inside a rack, yet) has temperatures from about 93-95F on average. Now, this wouldn't be much of a change even if I move it to the rack right now because the basement is actually less hot then my office. This just gives you the idea of how a different size and type of drive can have on the temperature side of things.

Again, taking all things considered, 100F+/- is fine. Less is better ofc, but not everyone has room for putting the NAS in an ideal space.
Thanks! Good To know. I will endeavor to keep my room cool.
 
Sorry, I am too much a technician to accept that...

My HGST 7200 rpm draws 11W when R/W (And 2 in raid1= 22W)
the SSD A400 draws 0.27 W so 0.54W in raid 1
Although part of that 22W is converted into noise, the rest is heat and should be removed.

Therefore it is clear that an SSD is much less likely to heat up the PCB of the NAS than a conventional HDD. Even though it is hotter locally, theoretically 50 times less cooling is needed!

Agreed on the plastic case around the SSD, that limits heat transfer and that increase the need for airflow. Anyway, I am still not ok with the fact that synology uses the same system and alarm Settings for ssd and HDD. I think they should discriminate between the two. And measure temperature a the point that matters, and not only at the disk itself.
 

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