Error during drive upgrade - RN104 with Seagate NAS HDD ST4000VN000

Fresh update:

After several attempts removing and once again building/syncing, it is producing the error: ERR: Used disks. Check RAIDar.

14th Apr, I purchased a new 3TB WD Blue drive (WDC WD30EZRZ desktop drive). I need this new HDD as a multipurpose buffer/spare/archieve/snapshot especially situations like these. After several reliability tests. Took the entire backup of my NAS data in the same. This took several hours due to 15MBps read/download speed. Anyway glad that I can able to read/retrieve everything. The WD Blue drive also worked very reliably so far. And noticed its temperature profile which is much better than Seagate.

Yesterday: 15th Apr, once the backup is 100% complete from NAS to WD Blue 3TB drive. Data is intact. Then I did a fresh NAS build. I built this time initially with 1TB Laptop HDD, 128GB SSD, 2TB Desktop HDD, (and removed the 4TB Seagate NAS HDD for a moment), this has reduced the fresh volume build/sync to just 12-14 hours.

The new build is successful. I documented the whole process in my Youtube VLOG (screen-capture):

https://www.youtube.com/watch?v=hQ0scDC239s

Once done everything, this time I set Network port mode initially: Active Backup

Benchmarked (1TB HDD, 128GB SSD, 2TB HDD): 23.5MB/s write, 26MB/s read

morning 16th Apr,

I changed initially to mode: Transmit Load balance: 30.2MB/s read, 26.4MB/s write

later I parmanently changed to mode: Adaptive Load balance: 31.6MB/s read, 27.5MB/s write

I managed dumping back some of the data from 3TB WD Blue drive to NAS since last night.

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Since now that NAS done 100% sync/rebuild, I now added back the 4TB Seagate NAS HDD in slot-4.

It started resync. May be once it is fully done, I may do once again a fresh benchmark of read/write.

It is a great learning curve. I think in future I may shift 100% to SSD Drives.

I see a great temperature difference between HDD vs SSD even in intense load.

I hope once it is all set, I never want to disturb again.

But its a great experience. I can see the future HDDs will become obsolete very soon by 2018-2019. SSDs are going to dominate and eventually replace HDDs.

Right now HDD manufacturers are able to make huge capacity drives, but they are also lacking in reliability. We can compare this aspect with older drives (2000, 2005, 2009 manufactured), vs the HDDs manufactured these days. So I may never buy again a mechanical HDD :)