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#1 2011-03-04 01:01:55

gurney
Member
Registered: 2007-04-24
Posts: 7

EXT2 versus EXT3

I have two DNS-323's and have recently updated both of them to firmware 1.09.  Now that EXT3 filesystem support has been around for awhile I'm considering switching to EXT3 from EXT2.   However, I'm still wary.  Seeing how D-Link had, then took away (then returned), support for EXT3, I'm wondering if I should go for it. 

The NAS's are on a UPS so the risk of power outage is relatively low.  Does EXT3's journaling give me much benefit, in your view?  I'm a UNIX/Linux novice and have minimal experience with either filesystem.

Any comments one way or the other, based on your experience with the DNS-323, would be greatly appreciated.  That is to say, I'm particularly interested in the EXT3 implementation on the DNS-323 as opposed to "theoretical" comparisons.

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#2 2011-03-04 07:53:23

dhub
Member
Registered: 2011-01-01
Posts: 112

Re: EXT2 versus EXT3

I vaguely recall there being some data corruption issues when ext3 is exported via nfs...

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#3 2011-03-04 17:51:49

FunFiler
Member
Registered: 2010-05-23
Posts: 577

Re: EXT2 versus EXT3

The general answer is EXT2 is faster, but less reliable. The inverse is true for EXT3, slower, but journalling allows for better recovery options.


3 * (DNS-323 with 2 * 2TB) = 12TB Running FW v1.08 & FFP v0.5
Useful Links: Transmission, Transmission Remote, Automatic

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#4 2011-03-04 22:45:16

gurney
Member
Registered: 2007-04-24
Posts: 7

Re: EXT2 versus EXT3

FunFiler,

Thanks for your response.  Have you used EXT3 recovery options on the DNS-323? 

I know that EXT3 should provide better fault tolerance but I'm concerned specifically about D-Link's ability to deliver (i.e. the implementation), given that it took years after the product launch to restore EXT3 support.  Plus there continues to be hints of "data corruption issues" using EXT3 on the DNS-323.  (See dhub's comment above.)

I'm hoping to find someone who can say "I've used EXT3 since it was reimplemented... and it really works because I've had a power outage and the journaling delivered as promised... No regrets."  Or something like that.

Given how many DNS-323's  DLink has shipped, I'd think there should be at least a few success stories.  Anyone?

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#5 2011-03-05 00:23:34

FunFiler
Member
Registered: 2010-05-23
Posts: 577

Re: EXT2 versus EXT3

I haven't had a failure in the DNS323 so I can't say, but I've seen it on one of my other linux systems and it was all handled by the O/S. Based on other user posts, I presume the issues are corrected on a reboot.

FWIW - I run one DNS323 as Raid 1 on EXT2, and another as independant drives on EXT3.

If I ever reformat, I'd personally go EXT3, I just haven't had a need to reformat yet.

Last edited by FunFiler (2011-03-05 00:24:49)


3 * (DNS-323 with 2 * 2TB) = 12TB Running FW v1.08 & FFP v0.5
Useful Links: Transmission, Transmission Remote, Automatic

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#6 2011-03-05 21:37:56

adambyrtek
Member
Registered: 2010-12-12
Posts: 27

Re: EXT2 versus EXT3

I don't understand why you are so afraid of ext3. For a decade this filesystem has been used on millions of high-reliability servers around the world. In fact it was explicitly designed to improve reliability of ext2, which I would never use on a device that stores important data.

When it comes to "recovery options", the DNS-323 firmware is just a simple Linux distribution with some proprietary software on top. D-Link didn't reimplement ext3 from scratch, they just had to provide support in their web interface. Like with any other Linux system, if the filesystem is not properly unmounted (eg. during power failure), the journal is replayed automatically on mount. In case of a more serious failure, you can always run e2fsck manually to verify consistency of the filesystem (which should be mounted read-only during the check).

Last edited by adambyrtek (2011-03-10 01:48:21)

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#7 2011-03-06 17:48:32

fordem
Member
Registered: 2007-01-26
Posts: 1938

Re: EXT2 versus EXT3

adambyrtek wrote:

I don't understand why you are so afraid of ext3. For a decade this filesystem has been used on millions of high-reliability servers around the world. In fact it was explicitly designed to improve reliability of ext2, which I would never use on a device storing important data.

If you read the original post and do the due diligence you'll have the answer to your question.


gurney wrote:

I have two DNS-323's and have recently updated both of them to firmware 1.09.  Now that EXT3 filesystem support has been around for awhile I'm considering switching to EXT3 from EXT2.   However, I'm still wary. Seeing how D-Link had, then took away (then returned), support for EXT3, I'm wondering if I should go for it. 

The NAS's are on a UPS so the risk of power outage is relatively low.  Does EXT3's journaling give me much benefit, in your view?  I'm a UNIX/Linux novice and have minimal experience with either filesystem.

Any comments one way or the other, based on your experience with the DNS-323, would be greatly appreciated.  That is to say, I'm particularly interested in the EXT3 implementation on the DNS-323 as opposed to "theoretical" comparisons.

The simple facts of this matter are that there was a problem with data corruption in the DNS-323 implementation of ext3, which led to it being removed (I believe in the 1.03 firmware) and later reintroduced - the original poster has a valid question and has stated it very clearly.

He is not interested in the theoretical & perhaps generic arguements of the advantages of ext3 and journalling over ext2 - his interest lies specifically in whether or not D-Link has fixed the problem that they had in the past and whether or not it's worth using ext3 ON A DNS-323.

Personally - I'm comfortable with the risks involved in using ext2, my DNS-323 is on a UPS, and having personally explored the performance penalties involved with ext3 (there is a thread over at the D-Link forum with the numbers if you're curious), I have chosen to stay with ext2 - however - since I have not used ext3 for anything other than limited performance tests, I am not in a position to comment on it's stability or whether the original corruption issue has been resolved.

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#8 2011-03-10 01:57:20

adambyrtek
Member
Registered: 2010-12-12
Posts: 27

Re: EXT2 versus EXT3

I admit that I don't know much about the past firmware issues. I had used Debian (which completely replaces the original firmware) with ext3 on my DNS-323 for quite a long time. Only a few months ago I migrated to firmware 1.08 with ffp, and I haven't experienced any ext3-related problems since then. The OP mentioned that he is a UNIX/Linux novice, so I tried to phrase my reply with this assumption in mind.

I still claim that I would never use ext2 on a filesystem that stores important data, because in this case data consistency is much more important than write performance (and UPS doesn't offer a perfect protection). I experienced data corruption on ext2 in the past (before ext3 was even created) and I wouldn't like to go through that again. Of course this is a trade-off, so your mileage may vary, and I'm not trying to convince you otherwise.

Last edited by adambyrtek (2011-03-10 02:04:55)

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