RN516 Expansion to 24TB?

[herbg]

I'm rapidly running out of storage space on my RN516, running OS 6.10.4.  I have about 1.64TB free of a total of 18.17TB of available space.  I'm running RAID 5 on 6 4TB hard drives.   I use this NAS to store my movie collection which feeds a separate PLEX server.

Files are backed up, via RSync Server, to a ReadyNAS Pro 6350 running OS 6.10.4, with 6 4B drives for a total volume of 18.16TB.  This NAS is also running out of space quickly.

My question is this:  What is the most economical way of expanding the total volume on both of these NAS's?  If I start with the RN516 first, replace all 6 drives with 6TB drives, and "factory reset" the NAS, will I get to about 24TB in total volume?  There used to be a calculator of sorts on the Netgear site at one time but I cannot find it.

Before expanding the RN516, I plan to 'clean up' the 6350 first as it contains old files that were backed up.  I will 'factory reset' the 6350 and a clean, empty 18TB volume.  Then, the RN516 will complete a full RSync backup, creating an identical copy of the RN516 on the 6350.

Once the RN516 is expanded with the bigger drives, I plan to 'back up' the files from the 6350 back to the RN516.  Once completed and verified, I start the disk expansion process with the 6350, assuming I can expand it beyond 18TB.

So everything hinges on the ability to expand the volumes past 18TB.  Can I do this on both the RN516 and 6350?

[herbg · Accepted solution]

Thanks for the valuable tips on Snapshots.  I will make sure all 4 NAS's are setup this way.   I've schedule in Scrubbing, Defragmentation, and Balancing to run every 4 months, after an initial run in January!

[mdgm]

Since you are running OS6 you can expand past 16TB and by more than 8TB. Those limitations of RAIDiator-x86 4.2.x do not apply.

If you are using X-RAID replacing two disks (one at a time, wait for resync to complete etc.) with higher capacity disks would be sufficient to get some vertical expansion.

Having said that there are advantages from creating a fresh volume with all the higher capacity disks in place.

[herbg]

Yes, I'm using X-RAID with the 6 4TB drives in Raid-5.

Is there a calculator or formula that I can use to determine the most economical path to expanding the volume?
If I'm replacing 2 drives in the NAS (one at a time, as you suggest), what is the impact of using a 6 TB vs 12TB
or even 16TB drives?  Trying to do some cost/benefit analysis on getting the most space.

[bedlam1]

The Raid calculator is HERE 

[herbg]

Perfect!  Although, I noticed it doesn't include 18TB harddrives yet!  

[herbg]

I'm using the ReadyNAS Pro RNDP 6350, running OS 6.10.4, as a backup to the RN516.  Any concerns about expanding the volume past the current 18TB (6 x 5TB X-RAID 5) as well?

[StephenB]

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@bedlam1 wrote:

The Raid calculator is HERE 

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Yes, but it doesn't really handle expansion.  

If you are using XRAID, and you upgrade disks to sizes that are at least as large as the largest disk already in the NAS, then the capacity rule is "sum the disks and subtract the largest".

So if you start with 6x4TB and upgrade two disks to 6 TB, you'd increase the volume size from 20 TB (~18.2 TiB) to 22 TB (~20 TiB).

As far as cost-effectiveness goes, it is generally more cost effective to upgrade fewer disks using sizes.

If, for example, we assume Seagate Ironwolf drives then

• Two 6 TB drives would cost about $320 at current prices, and you gain only 2 TB of space.  That works out to $160 per TB gained. Adding a third drive later would cost $160 and gain you 2 more TB ($80 per TB gained).
• Two 12 TB drives would cost about $600 and you gain 8 TB - costing $75 per TB gained.  Adding a third drive later would cost you $300, and gain you 8 more TB  ($37.50 per TB gained).

[herbg]

I've ordered 2 16TB Seagate Barracuda drives for each NAS.  Is there a practical limit to the size of the volumes on the RN516 & ReadyNAS Pro (OS6)?

[Sandshark]

There is no known limit except the huge (petabyte, I think) limit for BTRFS.  Is there a practical limit where CPU power or available RAM would start to slow things down, not that anyone has yet found, AFAIK.  Before moving to a rack-mount system, I had 6 x 6TB in a 516, with 5 x 4TB in an EDA500 and 5x3TB in another eSATA chassis.  Though the eSATA expansions were slow just because eSATA is not really suited for RAID, the 516 handled it all just fine as long as the expansion hardware behaved.

[StephenB]

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@herbg wrote:

I've ordered 2 16TB Seagate Barracuda drives for each NAS.  

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Are you sure they are Barracudas?  www.seagate.com goes up to 8 TB for the Barracuda, and 14 TB for the Barracuda Pro.

[herbg]

My error ... they are Ironwood Pro ST16000NE000 drives.

[StephenB]

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@herbg wrote:
My error ... they are Ironwood Pro ST16000NE000 drives.

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Ironwolf Pro are much better choices for your NAS.

[herbg]

Going through the Vertical Expansion right now, with one 16TB re-synced and the 2nd 16TB drive re-syncing.  Because X-RAID Raid5 excludes one 16TB drive from the overall volume, I expect the total volume to be 32TB once the 2nd drive has re-synced.  At least, I hope that is the way it will turn out.

Question:  Would I have achieved a larger total volume than 32TB if I just blew out all the data and built a new volume from scratch (on all 6 drives) on this NAS?  If so, how large would the resulting volume be? 

Thanks,
Herb...

[StephenB]

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@herbg wrote:

Question:  Would I have achieved a larger total volume than 32TB if I just blew out all the data and built a new volume from scratch (on all 6 drives) on this NAS?  If so, how large would the resulting volume be? 

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The capacity would be the same either way.  2x16 +4x4TB will give you a 32 TB volume (~29 TiB is what you'll see in the NAS web ui).

Technically this is done with two RAID groups - the 6x4TB RAID-5 group started with, plus a new 2x12 TB RAID-1 group that fills the remaining space on the 16 TB disks.

To expand again you will need to upgrade a third disk to 16 TB - which will give you a 44 TB volume. That will convert the 2x12 TB RAID-1 group to 3x12TB RAID-5.

[herbg]

OK ... that makes sense.  My new volume is 29.08TB - as you indicated.  The NAS has about 18 hours of resyncing left but I have a question about maintenance after this is completed.

I have bit-rot protection enable but snapshots were turned off to save space.  Now, with a larger volume, I plan to re-enable Snapshots again.

For maintenance, is Scrubbing, Disk Defragmentation, and Balancing advisable?  I have never used these utilities but the Knowledge Article is a bit confusing when bit-rot protection is enabled.  Since this backup NAS has been in used for 9+ years, I thought it was time to do some maintenance! 

[StephenB]

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@herbg wrote:

Now, with a larger volume, I plan to re-enable Snapshots again.

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FWIW, I always recommend against using the smart snapshots.  The problem with them is that the oldest snapshots are retained indefinitely, so eventually you will need to manually delete them for each share (or run out of space).

Instead, I suggest using Custom snapshots.  Here are the settings I use for most shares:

You can of course adjust the retention setting as desired - to balance the snapshot space against the benefit of keeping the older versions.

BTW, if you check "Allow Snapshot Access", for some reason the NAS will allow you to write to the snapshots.  Personally I think that's a horrible decision on Netgear's part, since for me the most important reason for snapshots is to ensure I have a copy of older versions.  So I also recommend against checking that box.

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@herbg wrote:

For maintenance, is Scrubbing, Disk Defragmentation, and Balancing advisable?  I have never used these utilities but the Knowledge Article is a bit confusing when bit-rot protection is enabled.  Since this backup NAS has been in used for 9+ years, I thought it was time to do some maintenance! 

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I don't think that the setting for bit-rot protection should affect your maintenance schedule.

I run each of the maintenance functions (include the disk test) once every three months (spread out over the quarter).    I don't see any need to run them more frequently myself.  

Scrubbing (and/or the disk test) can give you early warning when the disks begin to fail, since both tests require accessing every sector of every disk.  

With BTRFS, there is a distinction between free space and unallocated space.  The file system needs a reasonable amount of unallocated space to run properly.  Periodically balancing will reclaim unallocated space (from the allocated free space).  The frequency needed for balances depends a lot on your usage.  If it takes a long time, you aren't doing it often enough.  It usually completes in 15 minutes or less on my systems.  

Defrag is the hardest one to figure.  Too much fragmentation can hurt performance, but defragging also tends to increase the space needed for snapshots.  Many people choose not to run it at all.  If I were going to drop one maintenance function, it'd be defrag.

[herbg · Accepted solution]

Thanks for the valuable tips on Snapshots.  I will make sure all 4 NAS's are setup this way.   I've schedule in Scrubbing, Defragmentation, and Balancing to run every 4 months, after an initial run in January!