Does the number of drives I "can lose" w/o losing integrity change depending on how full the Storage Pool is?

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Does the number of drives I "can lose" w/o losing integrity change depending on how full the Storage Pool is?

jann

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I am just wondering...those of you who remember my horrific start w/my DS1520+ know that I did this wrong to begin with. Let's be nice to me and set that aside.

I put drives that were too large in my Synology to begin with and had to spend tons of $$ to go up from there when I expanded. (ie: Should've started w/my 8TB's, but inserted my 14's and 18's...thus I cannot convert my unused space to other usable space on a pool that is separate.)

What my question is is simple: With my (thank GOD) *ex* Drobo, if I had masses of extra disk space, it would then use extra space on some drives for extra parity and thus I could lose multiple drives and be fine. My Synology Pool is currently 52.73TB - with several of those drives NOT using 4Kn (my 16 & 18tb Exoses)...thus I lost about 2tb per drive. 4Kn rearing it's ugly head! Now that I am knowing where I messed up, I am wondering, can I remove one or more of the 18's since I am only using 30TB? ie: will the extra unused storage pool space on the drives allow me to "fail" more than one drive so I can then rebuild into another storage pool with 4Kn intact and move files over, then fail others until I complete the move?

Thanks!
ps: PLEASE don't flame w/"Start over. You can't do anything." not all of us can afford to buy 30TB of new drive space AND another Synology to create a new pool and move the data over. Thanks!

pps: the reason I'm asking is this vague statement on Synology's KB (I have 5 disks): "By selecting SHR Mode, Synology DiskStation will help you create an optimized storage allocation based on the number of installed disks. SHR volumes consisting of two or three hard disks provide 1-disk fault tolerance, while SHR volumes consisting of four or more hard disks can provide 1- or 2-disk fault tolerance." Synology KB
 
By selecting SHR Mode, Synology DiskStation will help you create an optimized storage allocation based on the number of installed disks. SHR volumes consisting of two or three hard disks provide 1-disk fault tolerance, while SHR volumes consisting of four or more hard disks can provide 1- or 2-disk fault tolerance
No conflict. SHR is one drive protection; SH2 is two-drive protection. Select what you require.

Read on here
 
When you start out creating a storage pool then there really is only a one-way street for adding drives for data and protection, there's no reversing. Assuming you have spare bays, and SHR, then...
  • You can replace smaller drives with bigger to grow data.
  • You can add drives to grow data.
  • On SHR-1, you can add a drive to increase protection to two drives (SHR-2)
What you can't do, and keep the storage pool Healthy, is remove a drive nor convert a N drive SHR-1 to N drive SHR-2.

If you remove a drive from SHR then it becomes degraded and the level of protection is reduced by 1 drive.
 

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