I have read just about every published ReadyNAS review, as well as relevant Netgear materials, including this forum. I have prety good understanding of file systems, NAS concepts, RAID, etc. Yet I am unable to find detailed answer to the question as in the title of this thread.I believe that Netgear is doing rather poor marketing job here. One of the main selling points of the new ReadyNAS series is data protection. Yet a potential buyer is left guessing. I am not alone in my confusion. Below a typical reviewer impression, quoted from Legion Hardware. Similar remarks can be found in other reviews:"we honestly don’t know how much safer your data is when using BTRFS over EXT4" (from Legion Hardware "Netgear ReadyNAS 312, 314 and 316" review)Can anyone answer and/or point to the materials answering this specific question in relation to ReadyNAS?

As far as I know BTRFS is safe, it is used as the default filesystem on some linux distributions. That said all the distributions do not use it and most of them use ext4 by default including the leading ones, RedHat and Debian. Ext4 is just an evolution of already existing EXT formats, so it already earned the trust. BTRFS is a newcomer and it may take years for them to finally get the trust ZFS has today (not sure they will ever come close to EXT, except if BTRFS blows it by 50% on every existing benchmark or add more killer features).The filesystem itself is still under development and many people would say that that status alone makes it unsafe. Now, Netgear folks tend to check their products before updating them and BTRFS guys seem to know what they are doing. So you have to ask yourself, do I trust Netgear (and BTRFS team) to do this checking for me, or do I prefer to use ZFS or some kind of LVM+ext4 combination. So if you want my opinion, I never experienced problems and I don't think I will see some. If you want an IT professional opinion, unless a product is final, it shouldn't be used for production. The question here is more about trust than anything else. BTRFS doesn't crash every 5 minutes, doesn't lose data and have no memory leak (or at least not big enough to fill my 512Mb memory in 6 weeks). I don't think that anyone has your answer except maybe BTRFS guys, exactly because it actually comes down to trust, you never know what the next update will get you. But that's also valid for microsoft that pulls back its patch tuesday a little too often nowadays...

BTRFS does provide file and metadata checksumming which is not available in EXT4. That alone should make your data safer. BTRFS also enables functions such as snapshots. That will protect your data from a major cause of data loss - human error. BTRFS and ZFS are the only two major file systems that can do this. NETGEAR works very closely with both file system communities and shares our improvements back to the community.I don't have any numbers on how often EXT4 would write the wrong data if you are looking for statistics.Here is a published article on the state of file systems. You'll definitely see more BTRFS enhancements over time.http://arstechnica.com/information-tech ... lesystems/

ReadyNAS OS 6 has been around for close to 18 months now. So we've been shipping products using BTRFS for quite a while now and we continue to have confidence in this filesystem.Over time I expect you will see major Linux distributions shifting to using BTRFS as the default filesystem.Regardless of what RAID level you use or what filesystem it is still important to note that backups are important. No important data should be trusted to a single device. While unlimited snapshots with BTRFS helps to protect you against common human error (such as accidentally deleting a file), there are some things that you still won't be protected against such as too many disk failures, fire, flood, theft etc.The ReadyNAS 516 has ECC memory which you may also be interested in.We do also have our ReadyDATA products which use the ZFS filesystem for those who want that.

You won't find anybody credible saying stuff like "btrfs is 283% safer than ext4". What you are seeing is some folks moving away from ext. Oracle started btrfs. Facebook is an early adopter - they hired lead btrfs developers and started apparently started rolling it out a few months ago. These are not companies that want to take risks with their data integrity. OpenSuse 13.2 will make btrfs their default file system in their distributions in November 2014, which will accelerate adoption. Netgear clearly believes in it - they knew they'd take a hit in the performance measurements, but they went with it anyway. But they aren't alone, there are some leading companies right there with them.BTW, btrfs is no longer considered "beta", and and the on-disk format is now viewed as "stable" - with software still undergoing rapid development. http://en.wikipedia.org/wiki/Btrfs

Thanks all for your feedback. I am happy with stability of ReadyNAS OS, I know about snapshots, etc. I remain curious how Netgear handles silent data corruption (AKA bitrot). It appears to me that Netgear did not make any clear declaration here, and that people reviewing ReadyNASes are also unclear about it. Often qouted Ars Technika article appears to be one of the very few attempting to demonstrate how BTRFS may handle that problem, but it does not appear to be aplicable here as it used different NAS configuration.What I am missing is not unrealistic assurance: "btrfs is 283% safer than ext4", but something similar to a statement quoted below (different product and file system) which would clearly say how specifically ReadyNAS handles silent data corruption. IT is clear from reading various sources that I am not the only one missing such clarification:"Protection from Silent Data CorruptionEnd-to-end data integrity requires that each data block be verified against an independent checksum. (...)uses its end-to-end checksums to detect and to correct silent data corruption. If a disk returns bad data transiently, (...)will detect it and retry the read. If the disk is part of a mirror or RAID group, (...)will both detect and correct the error: it will use the checksum to determine which copy is correct, provide good data to the application, and repair the damaged copy"

How much safer your data is when using BTRFS over Ext4?

17 Replies

Replies have been turned off for this discussion

StephenB

Guru - Experienced User

Sep 05, 2014

xeltros wrote:
Joke aside, adblock, do not track me and 1password are the only browser plugins I use... There might be a reason for that ;) This do not prevent some of the tracking (things based on the user account or the IP address) but it helps.

xeltros wrote:
Joke aside, adblock, do not track me and 1password are the only browser plugins I use... There might be a reason for that ;) This do not prevent some of the tracking (things based on the user account or the IP address) but it helps.

Private browsing, etc help, but as you say they aren't 100%. And for most people, the PC browser isn't the only source - there's social media, mobile devices and public databases also. The economic incentives for tracking are very significant, and "big data" mining comes up with a scary amount of information.

Basically, once we all accepted an ad-supported internet, we lost our privacy. If you look at the research, its hard to draw any other conclusion.

StephenB
Guru - Experienced User
Sep 05, 2014
garyd9 wrote:
umm.. I was sarcastically joking. Sorry for the misunderstanding.
And I replied thinking that. Though I think my reply is true none-the-less.
mdgm-ntgr
NETGEAR Employee Retired
Sep 05, 2014
garyd9 wrote:
umm.. I was sarcastically joking. Sorry for the misunderstanding.

I realise that, but I thought I should reply in case some users come across this thread thinking that you were being serious.
janpeter1
Luminary
Nov 02, 2014
Hi,

I agree with earlier contributors to this thread that Netgear (and reviewers) do not lift up the
possible (great) benefit for Readynas using BTRFS to minimize (certain kind) of silen corruption.

I think it would be very good with some clear statements here from Netgear personal in this forum
or people with similar background.

I also wonder if BTRFS capability to in principle eliminate certain kind of silent corruption
is mainly interesting for RAID-configurations with several disks. Does BTRFS give any advantage
for RAID-1 where you simply mirror disks? for instance. I recall vaguely the ARS-article which showed
what may happens to photos with silen corruption - but it was a RAID-system with several disks.

Personally I think I can take slower read-time, provided there is a benefit concerning silent corruption.
Thinking of large archives of photos and videos in a family for instances.
mdgm-ntgr
NETGEAR Employee Retired
Nov 02, 2014
Bit-rot protection is coming in 6.2.0.
janpeter1
Luminary
Nov 04, 2014
Very good!
Actually I thought it was already in place and the introduction now in 6.2 explains
the little focus on bit-rot protection from NETGEAR and reviewers.

I read the related thread below with great interest
viewtopic.php?f=154&t=77777
mdgm-ntgr
NETGEAR Employee Retired
Nov 04, 2014
We already had checksums so you could be alerted if bit-rot happened, but we didn't have bit-rot protection to be able to do something about that.

Forum Discussion

How much safer your data is when using BTRFS over Ext4?

17 Replies

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