DSM 6.2 Add/Expand SHR-1 with 20 TB drive

[Devious]

Good Morning/Evening

I wanted to upgrade my storage pool space (SHR-1 based) as it was screaming of low-space warning so I purchased (2x WD UltraStar DC HC 560 #WUH722020ALE6L 20TB) & like I always do, enjoy having (dive headfirst approach) & how much fun, knowledge, experience gain that comes with it, even though I did/do my research (kinda).

But, seems I got stuck so to speak, where I don't know how to approach my issue (in best way/practice/least effort/safe manner) & dig my self out of that.

First let me lay down my specs :

• Synology DS1621+ (DSM 6.2.4-25556 Update 6) **
• 16 GB RAM (2x Crucial Basics 8GB DDR4 1.2v 2666Mhz CL19 NON-ECC)
• 1x SK Hynix BC501 SSD Cache 256GB
• APC Back-UPS BX750MI
• 4x (WDC WUS21010ALE6L4 10TB)

**Note: Yes, didn't jump into DSM7 as of yet, as you can see from specs above not (Synology Products Compatibility List) & didnt like to see (WARRING/RED/AMBER..) in my status, except if there was really one

Steps taken (pre-expansion)

• Stopped all (File Sharing services running SMB/NFS).
• Stopped Download Station & Docker services.

Proceeded with info. gathered from below sources :

• Replacing 4tb with 14tb drives expanding SHR1 | SynoForum.com - The Unofficial Synology Forum (Thank you marco)
• Add Drives to Expand the Storage Pool Capacity | DSM - Synology Knowledge Center
• Replace Drives to Expand Storage Capacity | DSM - Synology Knowledge Center
• Replacing & expanding drives in SHR1 pool : synology
• Efficiently upgrade procedure for SHR-1 swap with larger drives : synology
• How to replace a drive on a Synology NAS with Synology Hybrid RAID (SHR) on DiskStation Manager (DSM) 6.2 · GeekBitZone.com - Passionate About Tech #Visuals to marco's post
• Drive order/slot importance (or not!) | SynoForum.com

What I've ended with is, basically back to square 1 unfortunately.

Backtracking my steps & reading closely to analyze my issue...

Drive wasn't fully utilized in my pool after repairing & based off snapshot from Synology KB's example above, although as i understood that SHR-1 allows to have different sized drives to be used in that manner!

So, here is my questions :

• When choosing to (Deactivate) a drive from a pool, does it remove any parity-checks/checksums rendering the drive as "rouge" ?
  • if yes, can i backtrack my previous step remove 20TB reintroduce old drive, rebuild & try another approach (more on that below) **Note: 18Hrs to rebuild give or take with my setup.
  • if no, then it would be as easy as having the drive back & fire up the synology again (less down time).
• Given the fact that synology is GNU/Linux (heavily customized Debian fork *so i heard*), is there a way to reclaim/configure unused space through SSH ?
• Last favorable resort (most time consuming)
  • Use extra two empty bays & populate with (20 TB + 10 TB) make a new pool copy data off to new pool.
  • Reinitialize old pool with 20TB drive populated & copy back data back.

Unorthodox approach :
- Use old drive, rebuild pool, use free bay adding new drive to pool to expand then (Deactivate/Remove) one of the 10 TB drives & rebuild again with new drive.

PS: 2 empty bays are kept for future/usage/expansion later on as am going to replace 10TB's with 20TB's based of outcome of my upgrade, hence using *one* drive & keeping 2nd *just in case*

Excuse my lengthy post, as I wanted to be clear & to serve as reference/knowledge for any one & future me
Thank you

 

[pbondurant]

There's so much verbiage in your Q that it's hard to follow what exactly you've done and are expecting.

To cut to the chase; if the issue is that you've replaced a 9.1TB drive with a 20TB and you're not seeing any increased space, this is to be expected. You need to replace at least one more 9.1TB drive with a 2nd 20TB; after it rebuilds you will have ~10TB extra space. By just replacing one drive, SHR cannot use the extra space as this space has no redundancy.

After that, you could choose to add the 2 removed 9TB drives into the 2 spare slots; this will give you 9TB extra again.

You cannot remove the 20TB drive and put the 9TB back because this violates point 1 in the quote from synology above ("the drive you add must be equal to or larger than the largest drive in the pool...").

If I've misunderstood the gist of your Q then maybe someone else can chime in.

hth

 

[Devious]

There's so much verbiage in your Q that it's hard to follow what exactly you've done and are expecting.

To cut to the chase; if the issue is that you've replaced a 9.1TB drive with a 20TB and you're not seeing any increased space, this is to be expected. You need to replace at least one more 9.1TB drive with a 2nd 20TB; after it rebuilds you will have ~10TB extra space. By just replacing one drive, SHR cannot use the extra space as this space has no redundancy.

After that, you could choose to add the 2 removed 9TB drives into the 2 spare slots; this will give you 9TB extra again.

You cannot remove the 20TB drive and put the 9TB back because this violates point 1 in the quote from synology above ("the drive you add must be equal to or larger than the largest drive in the pool...").

If I've misunderstood the gist of your Q then maybe someone else can chime in.

hth

Thank you pbondurant for answering my post/questions, as you have perfectly nailed it.
As I went on & done that prior to reading your answer & didn't get the chance to update my post with my results.
So, waited till it finished the whole process (expand/scrub) & post back here.

It was successful.

Oh, mind my lengthy post as I stated, to serve as knowledge/reference for (noobs) myself included.
Just learned a new word too "verbiage" thank you.