First time NAS user. Allocation of hard drive space, how to configure RAID, do I need to stay logged in?

[Charles_I]

I intend to use my new NAS drive primarily as file storage for editing video files. My plan is to have the 4 drives RAID configured with two drives for storage and the other two for simultaneous backups. I will also periodically manually backup these to an external drive. I do not want or need internet access.

I've setup the NAS (4 bay with 4 20TB drives) and created a Storage Pool (RAID SHR). The total capacity is now 54.5TB. I guess that the 54.5TB is three drives - but 5.5TB sounds like a lot for an operating system. The Storage Pool is 52.4TB. Another 2.1TB less.

Do I need to change the RAID configuration to accomplish what I want? How do I configure the RAID setup?

Do I need to stay logged in at all times to either the NAS or the Synology website? When I logged out I received an email notification that "Your Synology Account was signed out" with the message, "for security reasons, your Synology Account (my email address) automatically signed out from (my username)".

This is an initial setup so I have no data to lose and can install or reconfigure anything at this point.

Charles

 

[EAZ1964]

Well done so far, See the raid calculator:

RAID Calculator | Synology Inc.

Use this interactive tool to estimate the storage space of your Synology NAS when paired with different size hard drives and RAID levels.

www.synology.com

The redundant storage will take one disk.

Beware that “hard disk marketing TB” are not true TB. Something with better looking size when the use metric TB. 20 TB is 18.2 TB
The question has been raised many times, like :

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No need to redo any thing and You don’t need to remain logged in .

 

[EAZ1964]

Sorry, i missed the 2 disk remark on Backups.
Backups on the same nas are not real backups. You can do this in a separate shared folder if you prefer.
Setting op two pools of two disks cannot be done in a combination of secure and disk space efficiently, for most users SHR is a good balance, it allows for 1 disk failure.
A copy of your data on this SHR, or use of snapshots is most efficient.

 

[streithausen]

Well done so far, See the raid calculator:

RAID Calculator | Synology Inc.

Use this interactive tool to estimate the storage space of your Synology NAS when paired with different size hard drives and RAID levels.

www.synology.com

The redundant storage will take one disk.

Beware that “hard disk marketing TB” are not true TB. Something with better looking size when the use metric TB. 20 TB is 18.2 TB
The question has been raised many times, like :

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Accept third party cookies

View: https://www.reddit.com/r/synology/comments/12v14p5/is_18_tb_really_only_13_tb/


No need to redo any thing and You don’t need to remain logged in .

This is marketing vs SI units

so the difference is 1000 ~ 1024
means 1 GB is 0.9313226GiB

math. giga is 10^^9 (1000000000)
GiB is 1024^^3 (1073741824)
So my calculation is: 18TB are 16,3TiB

 

[EAZ1964]

Actually, it is 16.37 TB (16.370904631913 TiB)

 

[streithausen]

you are correct, my calculator only allows one digit after the decimal point.
although it was a cheap pocket calculator, the mortgages are usually cheaper with this one

or, if you like this more: i already excluded the reserved sectors of the HDD/ SSD

 

[Charles_I]

Thanks for all of this. The calculator shows that the 54.5TB is exactly where it should be. 18TB for "Protection" still sounds like quite a bit but that appears to be how the system works.

I forgot that SHR takes the place of setting up RAID so there is no choice of settings.

But now I'm confused about the actual usage of the 4 drives. As a test I put in 162GB of files in the shared folder (Volume 1) but the storage folder shows each drive's capacity at 18.2TB so where is it being saved? If I fill up the 54TB in the shared folder how do I know which one(s) to remove and replace with a new empty drive? If I wanted to put it back in later to read some old files, would it even be readable given that the NAS setup would now have a new drive in it? Is it better to just move all the files onto an external drive once the NAS is full and keep using the existing 4 HDDs?

If I physically connect an external HD via USB to backup the content will it see the shared folder? And, if as was recommended above, I create a second shared folder to backup the existing shared folder what will the external HD see?

Charles

 

[Rusty]

18TB for "Protection" still sounds like quite a bit but that appears to be how the system works.

Synology SHR is RAID5 fundamentally with a twist.

Considering you have identical drives there will be no difference in your current setup from a math standpoint.

With 4 drives in SHR, capacity of a single drive (20TB) is calculated as redundancy meaning that every drive will be part of the array and together accommodate all the data.

but the storage folder shows each drive's capacity at 18.2TB so where is it being saved

Pool storage and volume storage are two different things. Drives will always show the same capacity as it will the pool. The volume space will change depending on the data saved. Check Storage Manager.

If I fill up the 54TB in the shared folder how do I know which one(s) to remove and replace with a new empty drive?

If and when the need to expand the capacity of the volume comes you will replace any of the current 4 drives, one at a time. It will not matter what order you take as the existing data is spread across all the drives. Do not consider 4 drives in you nas as 4 individual drives because being part of the array involves RAID rules.

Is it better to just move all the files onto an external drive once the NAS is full and keep using the existing 4 HDDs?

External drives are individual disks with no protection so using them for anything other than a backup destination, might be risky.

 

[Birdy]

What is RAID5 ?
What is SHR ?

 

[Charles_I]

If and when the need to expand the capacity of the volume comes you will replace any of the current 4 drives, one at a time. It will not matter what order you take as the existing data is spread across all the drives. Do not consider 4 drives in you nas as 4 individual drives because being part of the array involves RAID rules.

At first you say I can replace "any" of the 4 drives, and then it looks as if I have to replace all 4 hard drives since the data is spread across them? Which one is it?

Yes the external backup drive will only be plugged in and turned on when backing up, that's what I do now without a NAS.

 

[strikes2k]

At first you say I can replace "any" of the 4 drives, and then it looks as if I have to replace all 4 hard drives since the data is spread across them? Which one is it?

Yes the external backup drive will only be plugged in and turned on when backing up, that's what I do now without a NAS.

I suggest you read the links Birdy provided above. They go in to detail about RAID5/SHR. Basically, in a RAID5/SHR array your data is written across all the drives, along with what is called "parity" data that can be used to recreate the data from a single missing/failed drive. When you have a failed drive or want to expand the array you can remove a single drive without compromising the array. If you were to remove more than one drive at the same time the array would crash. After you replace the one drive, the array will repair itself. When it has repaired itself, you can then replace the next drive in the array. Rinse and repeat until you've replaced all the drives.

 

[Birdy]

+1

 

[Charles_I]

OK I've read the links and now I'm thinking that I don't want either SHR or RAID because "You can expand the storage capacity of an SHR storage pool by either replacing existing drives with ones of a larger size or adding additional drives." (My italics). I already bought the maximum sized drives (20TB each) and filled all 4 slots with them thinking that as I fill each one up (or two) I could take them out, put them in storage and put in a new drive. But the way I read it, I would have to buy 4 new drives and start all over again as soon as I fill up 54TB which won't take long with video footage.

If I already have backups of the content that is going on the NAS there is no reason for me to have all of the protection against drive failure. I'm not running a business where several people need constant uninterrupted access to the files. This is for personal at home use.

So my question now is if I start again and format the drives without RAID or SHR how do I fill one drive at a time - like 4 external drives plugged into a desktop computer? Do I create one pool for each drive?

 

[wrldtvlr]

As you have discovered, most RAID configurations are about continuous availability, not backup or archive. If your intent is to fill up a drive with video files and then save those offline only, then yes, creating each drive as it's own btrfs volume would work just fine.

 

[EAZ1964]

You can create a pool and a volume on each disk and set it up as a simple volume.
Then, You can create public folders, that are located on a specific disk.

Honestly, the synology NAS are not intended to work like this as a NAS is so much more than a " docking station for disks".
Removing disks with the intention to put them back/switch in a later stage is not recommended practice. It may lead to issues and import proces ( as system partitions are on each disk).
Also consider NOT to format them BTRFS as Ext4 has much better support on other OS'ses
I would really advise you to rethink your strategy is swapping disks is not needed and not efficient.

 

[wrldtvlr]

I agree - you wouldn't want to routinely swap drives on a Synology NAS. My sense was the OP wanted to use two of the four drives for archive purposes.

Ext4 may be a little easier to use with other computers, but BTRFS offers far more features like snapshots, versioning and data scrubbing. That's a trade the OP will need to make.

 

[EAZ1964]

Ext4 may be a little easier to use with other computers, but BTRFS offers far more features like snapshots, versioning and data scrubbing. That's a trade the OP will need to make.

With the minor remark, that data scrubbing is only supported on Raid volumes with 3 disks or more.

Data Scrubbing | DSM - Synology Knowledge Center

Synology Knowledge Center offers comprehensive support, providing answers to frequently asked questions, troubleshooting steps, software tutorials, and all the technical documentation you may need.

kb.synology.com

 

[Charles_I]

OK so if it's not recommended to swap drives then the process should be once the shared folder is filled up move the older content onto external backup drives and keep using the same 4 discs.

But if I create a pool and a volume on each disk what happens if one of the discs fails? Does the NAS OS require all 4 discs to have the same original formatting so that if one fails you have to format all 4 again? Will the NAS still work with 3 discs? If you replace the failed one will it be recognized or do you have to format all 4 discs and start again?

I like the features mentioned that come with BTRFs and I'm not going to be using multiple OS's, so I think I'll keep that system.

 

[EAZ1964]

In case you have 4 basic disks: they are completely separated, if one fails, you lose the data on that disk and you can replace it with any disk, smaller or larger. The system will run as usual, (system is installed on all disks) but with a warning that a disk has failed.

There is one exeption: upon setup, by default, the first disk will contain your own installed "packages" (apps). You can change the package location to other disk (you cannot move them), but If that disk fails, you will lose functionality that came with these apps. So make sure you hyperbackup these packages.

BTRFS has advantages, but also some disadvantages: It takes a 6% overhead on disk space, is slightly slower than EXT4. Take care not to switch on checksums if your disk is heavily changing data like in a docker of database application as calculating and writing checksums will hit performance.

 

[zombiephysicist]

I hate to say it, but what you want would mean you'd have about only 16TB of actual storage.

Here is what I think you want to do.

Drives 1 & 2 set as SHR (for redundancy and growth potential) as Storage Pool 1. This is your main storage area.

Drives 3 & 4 as SHR as Storage Pool 2. This would be used for backing up your main storage area.

That means your main pool would effectively show you only have around 16TB of actual storage available.e You can do a HyperBackup of storage pool 1 to storage pool 2. This is important that they are on different physical pools. Why?

Well, from time to time synology 'upgrades' things like the filesystem (eg from EXT4 to BTRFS, or from a non encrypted pool to an encrypted drive pool) and the ONLY thing you can do is nuke your pool and rebuild it. By putting a backup on a separate pool, it lets you pave your main storage pool 1 and rebuild from storage pool 2.

Also, your backup probably wont need as many drives as your main pool as hyper backups tend to be of limited data and magically compress on the backup side.

Here's the problem, if your NAS only has 4 slots, you've basically turned 4 drives into kind of just one drive of useful space. Sure you have a lot more redundancy on your main pool and backup pool, but this is pretty limiting.

For a lot of my data I like to have 4 drives for my main pool and 2 drives for a backup pool, so for my needs, that is the minimum size of NAS. But even in such a NAS, you only get effectively 3 drives actual storage space because of all the backup and redundancy.

Things get a little better with an 8 bay as you can often get away with 6 drives for the main pool and 2 for the backup, in which case you effectively get about 5 drives of actual storage.

Not sure any of that will make sense, but it's offered in the spirit of being helpful and of things I wish I realized when I started with Synology.