There is no manual for the new firmware 6.2.0 release.A manual is needed to explain in better detail the new features, how to use them and what they are.I have several question in regards to 6.2.01. What is "scrub", how does it work? What does it do? About how long does it take? Is the time it takes to complete based on the volume size, or on the actual amount of data on the volume?2. What is balance? how does it work? What does it do? About how long does it take? Is the time it takes to complete based on the volume size, or on the actual amount of data on the volume?3. I do know what defrag is, but how does netgear implement it? how does it work? About how long does it take? Is the time it takes to complete based on the volume size, or on the actual amount of data on the volume?4. Disk test, how does it work? What does it do? About how long does it take? Is the time it takes to complete based on the volume size, or on the actual amount of data on the volume?5. In regard to the auto power on and off. If the NAS is busy doing a scrub, balance, defrag, or disk test. Will it turn off or will it complete the task then turn off? Same goes if it's busy with a backup or replicate. Will it turn off in the middle of those tasks as well? Or will it completed them first before turning off. 6. If the unit is powered off automatically, and there is a scheduled task to start at a time that the unit is powered off, will it automatically turn on and start the task? Or must we schedule the unit to power on before the task is scheduled to start?Those are just some of my questions I have that can't be answered from reading the manual to 6.1 firmware, and you have not released the manual for 6.2.0

The manual is being worked on and coming soon.1. This ensures the disks are properly in sync with each other. To see if there are any errors. This is based on volume size, as it is done a lower level than the filesystem. This should be run probably no more than every few months. It puts heavy stress on the disks and running it too often may shorten the life of the disks.2. This is a BTRFS balance. It is used to balance chunks on the filesystem. BTRFS allocates space for data and metadata. Sometimes it gets this allocation wrong. Running a balance occasionally is advisable. We use filters, so the space used on the filesystem is relevant. The more space is used on the filesystem the longer it takes.3. This is a BTRFS defrag. It defragments the filesystem. Usage on the volume is important, but also the volume capacity.4. This tests the disk. The capacity of the disk is what is relevant to a disk test not how much data is on the volume.5. If system tasks which would be unsafe to abort are running the system will not automatically power off.6. I will try and find out.

Is the disk test some form of SMART test? Does it involve only disk reads, or does it use disk writes? Does it read all the allocated blocks (e.g., all the files), or just some?

It is a SMART extended self-test.

mdgm wrote:The manual is being worked on and coming soon.1. This ensures the disks are properly in sync with each other. To see if there are any errors. This is based on volume size, as it is done a lower level than the filesystem. This should be run probably no more than every few months. It puts heavy stress on the disks and running it too often may shorten the life of the disks.2. This is a BTRFS balance. It is used to balance chunks on the filesystem. BTRFS allocates space for data and metadata. Sometimes it gets this allocation wrong. Running a balance occasionally is advisable. We use filters, so the space used on the filesystem is relevant. The more space is used on the filesystem the longer it takes.3. This is a BTRFS defrag. It defragments the filesystem. Usage on the volume is important, but also the volume capacity.4. This tests the disk. The capacity of the disk is what is relevant to a disk test not how much data is on the volume.5. If system tasks which would be unsafe to abort are running the system will not automatically power off.6. I will try and find out.Would you recommend running a balance then a defrag, or a defrag then a balance, or just a balance or just a defrag?

The key thing is to schedule these tasks to occur at a time when the NAS is lightly used if possible.Both the balance and defrag options are useful. I would recommend running both.Maybe do a scrub then a balance, a defrag then the disk test.

6.2.0 has no manual to download | NETGEAR Communities

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btaroli
Prodigy
Dec 03, 2014
Right, so bitrot protection, in this scenario, is Netgear's shorthand for checksum + self healing. I really did a double take when I saw that entangled with CoW... since you really don't need CoW to do bitrot protection. It is interesting that you note that some of this happening at the md5 layer (where the stripe is) and some at the BtRFS layer. Nice to know it's there, though. :)
mdgm-ntgr
NETGEAR Employee Retired
Dec 03, 2014
Where did you read that CoW is not necessary for Bitrot protection? BTRFS checksums depend on CoW and these checksums are in turn essential for bitrot protection.
btaroli
Prodigy
Dec 04, 2014
checksums and, more specificially, healing, rely upon BtRFS's (or md5 if that's the layer it's happening in ROS6) knowledge of extra copies of blocks and/or parity information at the block level with which it can attempt to recovery from checksum errors. That protection, in BtRFS, occurs even if I choose to disable CoW on a folder (like the one I keep my VM's in). Can I still snapshot that path? You betcha! I do it every single day in my Linux environments. And, yes, the snapshot will result in CoW as data diverges from the snapshot... but once the new blocks are written for the +COW path(s), it stops doing additional CoW on those blocks.

Yes, that can get messy after a long while... but it's part of the mix to be aware of when tweaking around with filesystem behavior. :)

Perhaps some details will diverge from this in terms of how Netgear implemented it (bringing md5 and BtRFS together), but without documentation that's hard to say. I can confirm how it works in a pure BtRFS environment.
Wildtexaschef
Aspirant
Dec 04, 2014
The large files are HD MKV/MP4 video files in the size of 25gb to 35gb.

So once written, they are only read.
btaroli
Prodigy
Dec 04, 2014
Then I really wouldn't worry so much about having CoW enabled... and the bitrot protection will likely be of great interest. :D
btaroli
Prodigy
Dec 04, 2014
Oh, that's hilarious. I just tried creating a new folder (share) on my 6.2.0 env and was quite amused by the default:

So I guess it certainly does allow for no COW and snapshots. ;) Or is that no bitrot protection and snapshots? This UI is very confusing, tying together two functions that aren't usually combined. It would be nice to be sure what that little checkbox does. I think I'll be keeping it turned on for my shares, in any event, since I rather like checksums AND CoW.
btaroli
Prodigy
Dec 04, 2014
Digging around a little more, I was looking at the new home dir setup options -- I rather like this change by the way! I see that we can now enable snapshots -- does that include personal TimeMachine vaules, if enabled, by the way? But I also see a per-user "Protection" checkbox. Does that translate to the "Bitrot Protection (COW)" on regular shares, or is it something else?
mdgm-ntgr
NETGEAR Employee Retired
Dec 04, 2014
Well the way we have implemented BTRFS using md raid would make some things different to simply using BTRFS.

https://btrfs.wiki.kernel.org/index.php/FAQ indicates that if you mount a volume with CoW disabled then checksumming is turned off. This suggests to me that checksums do depend on use of CoW, perhaps a bit like how snapshots make use of CoW.

Bitrot protection (well at least our implementation) does depend on CoW. If Bitrot protection is disabled then CoW is disabled.

Snapshots are enabled by default on x86 systems. Snapshots will work when CoW is disabled as has been discussed earlier in the thread.

mdgm-ntgr

NETGEAR Employee Retired

Dec 04, 2014

btaroli wrote:
Digging around a little more, I was looking at the new home dir setup options -- I rather like this change by the way! I see that we can now enable snapshots -- does that include personal TimeMachine vaules, if enabled, by the way? But I also see a per-user "Protection" checkbox. Does that translate to the "Bitrot Protection (COW)" on regular shares, or is it something else?

btaroli wrote:
Digging around a little more, I was looking at the new home dir setup options -- I rather like this change by the way! I see that we can now enable snapshots -- does that include personal TimeMachine vaules, if enabled, by the way? But I also see a per-user "Protection" checkbox. Does that translate to the "Bitrot Protection (COW)" on regular shares, or is it something else?

Yes snapshots for home shares is one of the new features in 6.2.0

Personal Time Machine is stored under /data/.timemachine so I don't think so.

That checkbox might be referring to snapshot protection. Can you post a screenshot?

btaroli

Prodigy

Dec 04, 2014

mdgm wrote:
https://btrfs.wiki.kernel.org/index.php/FAQ indicates that if you mount a volume with CoW disabled then checksumming is turned off. This suggests to me that checksums do depend on use of CoW, perhaps a bit like how snapshots make use of CoW.

mdgm wrote:
https://btrfs.wiki.kernel.org/index.php/FAQ indicates that if you mount a volume with CoW disabled then checksumming is turned off. This suggests to me that checksums do depend on use of CoW, perhaps a bit like how snapshots make use of CoW.

I see... mount options. OK. I get that. And I should clarify that, in my environments, I leave all default filesystem features enabled but selectively disable COW on a sub-folder level, and very selectively. If I only wanted COW enabled on a limited basis, I'd just split the activity off into it's own subvolume (or, in ROS6-speak, folder/share).

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6.2.0 has no manual to download

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