It was a toss up for me.
1st was that I wanted to use 3.5" HDD
I was looking at both the DS418 or the DS918+
They are both 4 bay hot swappable units
The 918 can be expanded with a 5 Drive bay expansion unit, where the 418 can not.
Since I will only use it for personal use.
I decided that the ability to Expand it, and the other extra features of the 918,
weren't a requirement for me.
I went with the DS418
I did consider the DS418J unit, But it does NOT have Hot Swappable drive bays.
So I ruled that out for me.
The DS418J Might be a good solution for anyone looking to Add more storage.
These are Diskless - Meaning you have to Purchase the HDD separately.
So the Storage capacity is determined by the Size and Quantity of HDD you put in them, and the type of
RAID you use.
the 418j is around $300 - $350
the 418 is around $400 - $450
the 918 is around $550 - $600
- HDD cost is in addition to the cost of the NAS.
Compare features of all 3
https://www.synology.com/en-us/products/compare/DS418/DS918+/DS418jI've only presented 4 bay NAS units.
Because you need at least 3 Drives to build a RAID 5 redundant storage system.
You can't do that with less than 3 drives.
Raid size calculator
https://www.synology.com/en-us/support/RAID_calculatori put in (4) 4TB HDD for a total of 16TB in Raid 5
this net me 10.9TB of redundant storage.
( 4TB is the Decimal Size, but the HDD is actually 3.65 TB of Binary storage )
(Raid 5 - One HDD is used as the Parity Drive, so you Get the Storage capacity of all the drives minus 1 )
4 drive minus 1 = 3
3 x 3.65TB = 10.9 TB
In raid 5, any 1 of the HDD can Fail, and you are still protected.
Replace the Failed Drive, and it will be rebuilt on the Fly.
What is SHR and RAID
Use SHR if you have Mixed Sizes of HDD
Use SHR or RAID if you Have all the Same size HDD
https://www.synology.com/en-us/knowledgebase/DSM/tutorial/Storage/What_is_Synology_Hybrid_RAID_SHRPictures:
- 1) (4) 4TB Drives in Raid 5 give 10.9 TB net storage
- 2) All 4 drives are the same - details of the drive
- 3) I created 2 volumes, a 100GB and a 10TB volume. I'm currently using 49%