SSD Cache after upgrading is doing constant writeback to volume (HDD noises)

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SSD Cache after upgrading is doing constant writeback to volume (HDD noises)

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Hello :)



I have a strange thing going on with my DS920+ and new DSM 7.0 and its SSD caching. Im using 2x 500 GB Samsung 970 EVO which are on compatibility list for DS920+.

I ve done an upgrade from DSM 6 to DSM 7 months ago but few days ago I noticed that my SSD Cache is telling me that its not in a newest version. So I google and the problem is, that DSM 7 can utilise SSD Cache in better way with some applications and use metadata for Hyper backup and ABB.

So I deleted my SSD Cache and set a new one.

After this setup I noticed that HDDs are constatly awake, doing noises like constantly witing small amout of data every few seconds. And this is a screen of running proceses.

1637868844_DM4l6.png


I know that it should be writeback from SSD to Volume but its doing all the day except some hours and even when there is no work on NAS for a long time.

I tried to check and uncheck the Metadata usage and still the same thing happens.

I heard from Synology technician, that if you use only read cache its working, but why you shoudl do that if you have two SSDs installed.

Also removing the Cache solves this problem.



Has anyone experinced smth similar?

Thanks
 
Hey there,

i have the exact same Problem! With my new 1821+ and 5 EXOS drives + 2TB SSD cache.
The SSD writeback is constantly around ~500kb and the HDDs do this crazy wirteback noise.
Did you fixed it somehow?

Greetings and Thanks
Hope somebody could help.
 
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Seeing something similar on 2x 720+'s.... but I'm also doing Cache advisor on both, so I attributed that Advisor running for the results....
One 720+ SHR has 6TB Ironwolf 7200's, with 2x 512GB Samsung 970 EVO Plus Caches
Other 720+ SHR has 2x 1TB 7200 Barracuda's that reported on 7 Install Not to be supported but used them anyway, with 2x 256GB Ironwolf 510 Caches

Seeing/Hearing same thing you are reporting... On both.. But... I have Cache Advisor running on both...

I'll turn off Cache advisor and post tomorrow...
 
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After this setup I noticed that HDDs are constatly awake, doing noises like constantly witing small amout of data every few seconds. And this is a screen of running proceses.

1637868844_DM4l6.png


I know that it should be writeback from SSD to Volume but its doing all the day except some hours and even when there is no work on NAS for a long time.


So that when I check later tonight. Where were you when you saw this ??
So that when I check later tonight. Where were you when you saw this ?? Not seeing anything like that in Logs..
Thanks

By the way... I've been Sitting beside the older of the 2 720+'s.... for 15-20 min...
The one that upgraded from 6, And Since Cache Advisor has been turned off.... This system is now very quiet.... Cache Reports 100% Hit rate...now...
Other one is upstairs in bedroom, will test/listen that one later this evening... But it now reports a 99% Hit rate...
Both are set for same hibernation: 20 Min inactivity before hibernate... Both have 1x 3/4" Velcro Dot per drive stuck to NAS chassis as sound deadening.
 
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Been listening to new 720+ (Started life as v7) for a while now. Just as quiet as other one. Just occasional sounds from camera data, nothing with any regularity.

Only difference between louder sounds from last night and quieter today is: I turned off Cache Advisor…. And earlier today I turned off memory compression (No change in memory, and maybe a little less CPU)..
I did forget to mention before that I don’t have Active Insight enabled on any NAS, either.

So the sounds I heard with regularity before were Cache Advisor generated.

Also. I compared the sound of my 718+ in comparison to old 720+ (Both have 2x 7200 6TB Ironwolf’s). Both upgraded from v6.
Can’t say I hear a difference between them. All relatively quiet.
end of test.

PS. I have 14 Timed script files running on 718+ Starting at midnight, separated by 5 minutes each.... This, in conjunction with Shared File Sync, causes a lot of disc activity on all NAS's between 12 Midnight... and 1:15 AM I fell asleep at about 12:15 faintly hearing the 'Trickle down' Activity start... and awoke about 1 and decided to listen again... by about 1:15 or so activity on New 720+ Ceased, and it became quiet again....
 
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Hello both of you. We didnt come to a solution with Synology support. They checked the NAS and wanted some more testing but I didnt have time to solve that thing was about 2 weeks of reporting.
I thought the new udpates would fix this but not. In the end I removed the cache and sold the NVMes becuase I was having the ssd cache just for testing purposes.
Cache advisor is definetelly not a problem beuause I wasnt running that.
 
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I just reinstalled the SSD cache several times - but everytime the same - the synology starts immediately with the "writeback" process. Any Solutions yet?
 
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Where are you seeing this information? I'll look for it too, but I don't belive it's happening here from what I've "Heard"
(2x 720's with R/W Caches: 1 with 2x Seagate Ironwolf 510's at 256Gb, other with 2x Samsung EVO Plus at 500Gb Both at 7.1-1)
 
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