I have new four-bay NAS (Synology DS418play) and four new 4TB HDDs (WD40EFRX). Is it advisable to put all disks into NAS right away, even if I do not need the full storage capacity? Or should I put just two of them (one for storage one for redundancy) and add the remaining two disks later when I need to increase the capacity? I guess, I stick to Synology Hybrid RAID mode. Which of the two approaches is preferable and why?

1 Answer 1


If you put all 4 disks into a Raid 6, then 2 drives can fail -> 8 TB useable

Raid 5 over 3 disks might be faster, but then only one should fail -> also 8 TB capacity - you can keep the 4th as cold standby or hot standby.

Standard Raid levels are also explained by Synology.

With the RAID Calculator you will see that capacities of Raid 5 can be compared with SHR. Raid 6 can be compared with SHR-2.

According to this description of SHR you will see that it may be useful, if you later want to replace the drives with larger disks without downtime - but keep in mind that you still should have backups.
On the other hand you can not use SHR, if you want to add a 2nd redundant NAS.

  • If you have spare HDD's then over time you will probably use them in something else then when one from the nas fails ..... no disks. Always fill up the NAS Apr 21, 2020 at 21:40

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