Linked by Rahul on Fri 31st Oct 2008 16:12 UTC
Linux InternetNews talks to developers and vendors about the rise of Btrfs as a successor to Ext4. Though Ext4 adds extents, Chris Mason, Btrfs developer noted that BTRFS adds a number of other features beyond that. Among those features are items like snapshotting, online file consistency checks and the ability to perform fast incremental backups. BTRFS (pronounced better FS) is currently under development in an effort led by Oracle engineer Chris Mason. With the support of Intel, Red Hat, HP, IBM, BTRFS could become the engine that brings next generation filesystem capabilities to Linux.
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RE[4]: Funny
by Arun on Sun 2nd Nov 2008 22:46 UTC in reply to "RE[3]: Funny"
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"Please elaborate how you go about fixing something you can't even detect?

The odds are that you can't fix it anyway, so you're screwed either way - unless you have redundancy regardless. If you have redundancy then that's the only way you will be OK. Either that or you use an OS with decent device drivers or change your hardware ;-).

Don't beat around the bush answer the question.

How do you know to change your hardware if you can't detect the problem in the first place. Wait for lots of data to get corrupted over days and months? When that happens your backups get corrupted too because you didn't know you had corruption with it being "silent" and all.

"Again if you have no clue it is happening how do you go about fixing it?

You use something that works to start off with, or you switch mighty quick. Whatever happens, you're screwed without redundancy no matter what silent corruption you think you've detected, or what you can't detect either.

Answer the question. If you can't then say so. How do you know it works to start of with if you can't detect any corruption that might be happening?

"Again if the end user can't detect corruption since it is "silent" how does one inform the developers or hardware guys?

Users can't inform the developers or hardware guys because you won't know what has been detected at all and won't be able to give them anything. It will only be useful as a troubleshooting tool for developers to work through something that is reproducible.

Again no real answer. How do you know something bad is happening if you have no way to detect it?

Most people have no idea how to fix their cars. But car manufacturers put diagnostic information on dashboards so end users can know something is wrong and take it to get fixed.

Your silly argument is that since most people can't fix their own cars there should be no sensors or On Board Diagnostics in production cars. Information symbols, like low coolant, check engine lights, codes etc that tell people that something is wrong shouldn't exist in the field. Furthermore only the manufacturers of cars should use the system when they develop cars because that is the only place errors happen.

People with real world experience will realize that hardware can go bad over time while in use. Especially disks. Not all issues are bugs in hardware. Bugs in FW and drivers are also important. If you have ever done system level software development you would know that some bugs are damn near impossible to reproduce in development environments and only happen in corner case scenarios in the field. In such cases having a indication that something bad is happening can be invaluable.

Linux's development cycle wouldn't include beta/unstable releases for people outside the core developers if all bugs could be found in the handful of configurations developers have access to. Bugs in linux would never exist after the final release phase because all permutations would have been tired in Beta. If you believe that I have some really bad news for you about Santa Claus.

"The only place it hasn't generated any excitement is in your head. Everyone else including BTRFS developers and Gentoo developers took notice and are doing something about it. Meanwhile you are still trumpeting a very flawed view point.

Yer, it's created a moderate amount of excitement - amongst developers. They will use it to recreate scenarios where corruption has taken place, find out what has happened in various device drivers and/or inform hardware manufacturers what has been going wrong with their hardware. Users will feel the indirect benefits of it but they will carry on as they have always done because they can't do much about it.

Wrong those features are for end users. If it was only for developers then it would only exist in debug builds. But it is an advertized feature for end users. Oracle is developing BTRFS, they obviously saw the need and are funding a completely new file system. If existing technologies sufficed why would they spend the money. Unlike what you say it isn't some independent OSS developers wet dream project.

Go ahead and show me proof that BTRFS' checksums are only meant for developer debugging.

"CERN did silent data corruption research and found it to be a major problem.

Good for them. Did they actually go through 20TB of their own data and actually find out how much corruption they had, did they actually fix anything or did they just produce some numbers? ;-)

Yes and they developed all sorts of application level error checking because no suitable OS feature existed. If you had read the PDF you would have known not to ask what was already in the paper. Goes to show you are not really here to provide an meaningful discussion on filesystems and data integrity. Just like you troll on every Sun and ZFS related topic with your silly theory on data corruption.

Your warped view of the perils of Silent Data corruption notwithstanding. Most sane people realized the need to detect it. I am glad those people are actually doing some thing to fix it (BTRFS).

The bottom line is this discussion is about if filesystems should have measures to detect corruption. Nothing to do with ZFS especially since BTRFS is advertizing the same capabilities for linux. Your contention is that they shouldn't. Yet you can't seem to answer a simple question.

How do you know you have problem is no mechanism exists to detect it?

Edited 2008-11-02 22:48 UTC

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