LWN: Comments on "Fedora 16 to use Btrfs as its default filesystem"

Fedora 16 to use Btrfs as its default filesystem

ssam — Tue, 21 Jun 2011 13:26:56 +0000

backing up on macosx is very easy, so that might be a fairly big chunk of the 8%.

maybe the distro installers should be asking people to choose a backup device.

SATA and hot plugging

nye — Mon, 20 Jun 2011 15:46:52 +0000

>You do need to have AHCI enabled in the BIOS for eSATA hotplug to work - most modern motherboards support this, and Windows 7, but if you are dual booting with Windows XP you may have to revert to the non-AHCI mode.

FWIW, if you had Windows XP pre-installed or if you managed to get the correct driver to the Windows installer[0] then you should have no problems with AHCI, but once it's installed Windows (XP at least) is very unhappy if you switch between AHCI and non-AHCI. Linux of course has handled the change transparently for years.

[0] Via learning how to make a slipstreamed install disc, or doing the "find an old floppy disk drive, install it to an existing machine, find 4 billion old floppy disks in the cellar/loft/garage, spend 6 hours finding one that still works reliably, save the driver to it, install the floppy disk drive in the new machine, install Windows and press F6 at the appropriate time" dance.

Fedora 16 to use Btrfs as its default filesystem

lab — Sat, 18 Jun 2011 14:42:44 +0000

> If you think that personal backup solutions are used ..(snip)...

As "depressing" as it sounds, I would have to agree with you. In my experience through a couple of decades as the "home computer support guy", I would say, that the overwhelming majority of people consider (all forms of) computers as utilities that needs to just work automagically the way they want them to. I have (very slowly) resigned to the fact, that nothing I will ever say or do is going to change that. That is also why I think that ChromeOS (and the likes) should gain widespread usage - it's simply the only way forward.

Fedora 16 to use Btrfs as its default filesystem

elanthis — Fri, 17 Jun 2011 23:15:40 +0000

Analogies are like swiss cheese: full of holes and often smelly. (But now that means that they taste good on sandwiches and are good for catching mice.)

software nags some into backing up

skierpage — Fri, 17 Jun 2011 22:02:06 +0000

8% performing regular backups sounds about right. System "security" software nags you to make backups. E.g. my family Thinkpad running Windows has Lenovo's ThinkVantage Rescue and Recovery software nagging to make backups, and also the Norton 360 anti-virus icon displays an angry red X if you don't make regular backups. Alas the two programs don't understand each other, the former wastes disk space unless you manage backup generations, and the latter is dog slow navigating files to restore and doesn't backup the right directories for email software like Thunderbird and SeaMonkey. But if users with such utilities on their system bother to make the checkmarks go green, they're doing some kind of backup.

(I don't trust either of them, I occasionally fiddle with Unison and rsync to synchronize key directories to a storage drive where I can see files.)

Fedora 16 to use Btrfs as its default filesystem

jeremiah — Fri, 17 Jun 2011 15:37:10 +0000

I think FOSS developers are a little more diversified than you might think. Last summer my son and I wrote an asteroids clone together. This summer were putting a super charger in a Mustang GT, and rebuilding the engine in our tractor. All the while debating the pros and cons of open core vs. open, and GPLv3 vs. GPLv3 Affero for our startup. And I don't think this is unusual or rare. I think OSS developers all tend to be more jack of all trades and fix it them self types. Given that we like to fix the code our it kinda implies that we like to fix the things in our wetware lives as well.

Sorry for the off topic, but was just trying to figure out what kind fuel injectors to get this morning so your post just struck me. :)

grub support?

mebrown — Thu, 16 Jun 2011 19:48:09 +0000

I wrote the anaconda patch for GPT support way back for, iirc, Red Hat 7.2. It has been pretty much required for Itanium support for a long time, so even though that stuff has been rewritten a couple times since, I'm sure it all works.

SATA and hot plugging

Cato — Thu, 16 Jun 2011 10:21:02 +0000

You do need to have AHCI enabled in the BIOS for eSATA hotplug to work - most modern motherboards support this, and Windows 7, but if you are dual booting with Windows XP you may have to revert to the non-AHCI mode.

Fedora 16 to use Btrfs as its default filesystem

Cato — Thu, 16 Jun 2011 10:13:41 +0000

Some corroboration of this is the huge demand for data recovery tools and services, which wouldn't be required at all if the average casual user did good backups.

grub support?

HelloWorld — Wed, 15 Jun 2011 23:51:28 +0000

legacy grub as *one* simple config. grub2 has such complicated config file that a script is needed to create it. That's a big step forward in the correct direction...

The grub2 configuration file isn't complicated. A typical config for grub legacy may look like this:

timeout   5
default   0
title  Arch Linux
root   (hd0,0)
kernel /vmlinuz26 root=/dev/sda3 ro
initrd /kernel26.img

set timeout=5
set default=0
menuentry "Arch Linux" {
  set root=(hd0,1)
  linux /vmlinuz26 root=/dev/sda3 ro
  initrd /kernel26.img
}

(examples taken from the Arch Linux wiki). As you can see, the differences are trivial. The reason that the grub2 configuration is created by a script is that the configuration needs to be changed when your distro ships a new kernel. Of course, this applies to grub legacy as well, so distros like Debian shipped code that does just that: generate a configuration file for grub legacy. The only difference is that grub2 actually ships the code that the distributors used to write for grub legacy (update-grub on debian, grubby on Fedora etc.). So please, stop trolling already.

grub support?

cortana — Wed, 15 Jun 2011 10:20:46 +0000

> However... the grub->grub2 transition annoyed me in several ways. There were a lot of changes that just seemed gratuitous. Why did partitioning numbering change to start at 1 rather than 0?

I think this was to bring it in line with how everyone else numbers PC partitions. 1..4 are the primary/extended partitions, 5+ are the logical partitions. Having to subtract one whenever I dealt with Grub was frankly annoying so I am glad they made the change. :)

Fedora 16 to use Btrfs as its default filesystem

rahulsundaram — Wed, 15 Jun 2011 08:42:56 +0000

30 seconds googling is not enough to verify any facts. Just see some links. I honestly don't know what average users do and don't really care. My statement on backups should be read in context which has nothing to do with average users anyway but people who are trying btrfs now.

Fedora 16 to use Btrfs as its default filesystem

jezuch — Wed, 15 Jun 2011 08:40:21 +0000

> 92% of users do not perform regular backups

On the other hand it says that as many as 8% of users *do* perform regular backups. Isn't it kinda optimistic? ;)

grub support?

zlynx — Wed, 15 Jun 2011 04:30:42 +0000

Fedora 15 successfully installed a GPT and EFI system on this notebook I am using. I think it works.

Fedora 16 to use Btrfs as its default filesystem

elanthis — Tue, 14 Jun 2011 21:12:31 +0000

When you spend 30 seconds googling, you easily find facts and studies. :)

Here's the very first link for "user backups study" which incidentally claims that 92% of users do not perform regular backups. The results page on Google has a number of other such papers and reports from other sources.

http://www.backblaze.com/press-June-is-Backup-Awareness-M...

grub support?

k8to — Tue, 14 Jun 2011 19:16:10 +0000

> > I never said that grub2 was a "huge mess". That was a different poster. Please read more carefully.
> I never said explicitly or implicitly that you did. Please read more carefully.

Bystander, it was defenitely implied by the text.

Hotplug

bronson — Tue, 14 Jun 2011 18:25:49 +0000

Always ensure a good ground first. Ground is on the power cable.

Actually, for sata it shouldn't matter too much since the data cable has longer dedicated ground pins too. But, in general, power first.

Hotplug

nye — Tue, 14 Jun 2011 11:08:30 +0000

So if one were to try hotplugging a SATA drive, what would be the correct order of connecting/disconnecting the power and data cables?

Fedora 16 to use Btrfs as its default filesystem

epa — Tue, 14 Jun 2011 10:17:11 +0000

Sounds cool. So you can stuff as many video cards into your system as you want, plug lots of USB keyboards and mice, and magically it becomes two or more desktops?

Fedora 16 to use Btrfs as its default filesystem

motk — Tue, 14 Jun 2011 06:21:26 +0000

Or it could be that nobody particularly cares?

LVM and rescuing systems

zuki — Mon, 13 Jun 2011 23:34:26 +0000

Yeah, it has worked fine for years. Some years ago the hotplug mechanism would work -- ie. the autodetection of new drives wouldn't work, hence the sata coldplug patches -- but nothing would break, but for a long time it has been working perfectly.

grub support?

HelloWorld — Mon, 13 Jun 2011 21:04:07 +0000

> I never said that grub2 was a "huge mess". That was a different poster. Please read more carefully.
I never said explicitly or implicitly that you did. Please read more carefully.

> The way grub-legacy works for me on Fedora is that I can edit /boot/grub/grub.conf, and the distribution can also edit that file during software upgrades.
Yes, that is because Fedora developed a utility named grubby that is able to read and edit configuration files for grub legacy, lilo and elilo, but not grub2. So your problem has nothing to do with grub2 but with grubby.

grub support?

cmccabe — Mon, 13 Jun 2011 20:43:40 +0000

> I understand that people dislike unnecessary changes, but you must
> admit that this is hardly a reason for calling grub2 a "total mess".

I never said that grub2 was a "huge mess". That was a different poster. Please read more carefully. I do think the transition could have been managed better, though.

> When your distro installs a new kernel, a new entry needs to be generated
> in the boot loader, which is usually done by generating a new
> configuration file from scratch, overwriting the old one. On Ubuntu at
> least, it works that way for both grub legacy and grub2, so there's really
> no difference in that respect

The way grub-legacy works for me on Fedora is that I can edit /boot/grub/grub.conf, and the distribution can also edit that file during software upgrades. I suppose you can argue that having part of a file be auto-generated, and another part be hand edited isn't "clean," but it is simple and it does work pretty well for me. In grub2, obviously, I have to remember not to change that file, because it will be completely destroyed by the auto-generation system.

I guess maybe the biggest benefit of the new multi-file structure will be to people doing package management. For some reason, that isn't mentioned a lot in these discussions.

grub support?

chad.netzer — Mon, 13 Jun 2011 17:30:34 +0000

The ability to handle multiple partition types is now important even in the PC world, as single drives can be >2TB and must be partitioned w/ GPT. The ability to handle both modern and legacy partitioning and filesystems, seems a reasonable justification for the modularity and extensibility of grub2.

Hotplug

tialaramex — Mon, 13 Jun 2011 16:59:53 +0000

The only scary bit of hotplug is the connector design, which I believe is correct for SATA as well as eSATA. The connector needs to be designed so that pins connect and disconnect in a well defined order. You can see this on a (standard) USB connector where a system ground (metal outer sheath) is connected first, then the USB power, then the shortest pins are data.

If that's done right then it rules out all the terrifying electrical mishaps that might otherwise be possible. Beyond that yes, a modern AHCI implementation should be capable of ensuring that a disk is quiescent, and cope with it subsequently vanishing, and then cope with a new device appearing and properly initialise it.

Early SATA hardware sometimes did not include the actual hotplug mechanism (ie waking up the driver and telling it a new device was added). But even then, as with IDE where hot plug wasn't intended to be possible at all, the operator could just prod the driver to take another look and see whether there isn't in fact a new device connected to a specific port. Not as user-friendly, but in the context of 'type pvmove' probably adequate.

grub support?

tzafrir — Mon, 13 Jun 2011 13:58:33 +0000

With grub1 in Debian (and IIRC also Ubuntu), /boot/grub/menu.lst was both a configuration file and a generated file. A special section of it was re-generated by update-grub . Configuration for update-grub was in lines beginning with a single '#' mark.

Works well. But not really a standard way to handle configuration.

grub support?

HelloWorld — Mon, 13 Jun 2011 12:22:23 +0000

> However... the grub->grub2 transition annoyed me in several ways. There were a lot of changes that just seemed gratuitous. Why did partitioning numbering change to start at 1 rather than 0?
I understand that people dislike unnecessary changes, but you must admit that this is hardly a reason for calling grub2 a "total mess".

> With the old grub, I only had to edit one config file, /boot/grub/grub.conf. My changes took effect immediately after editing this file. That was touted as one of the big benefits of grub over lilo-- with lilo, you had to re-run lilo every time you edited the lilo.conf. But now, I have to re-run update-grub every time I edit the grub2 configuration files.
When your distro installs a new kernel, a new entry needs to be generated in the boot loader, which is usually done by generating a new configuration file from scratch, overwriting the old one. On Ubuntu at least, it works that way for both grub legacy and grub2, so there's really no difference in that respect.

Also, unlike grub legacy, grub2 offers a simple and clean mechanism to add custom entries: just put them in /boot/grub/custom.cfg. You don't need to run update-grub in order to pick up changes in that file.

> Also, the number of configuration files for grub2 seems excessive. I only need one file to configure sshd, but just passing control to the kernel is now so complex that it needs an entire directory worth of shell scripts-- some of which are generated by other shell scripts?
Shell scripts aren't configuration files but code, and besides that, all the scripts in /etc/grub.d are hand-written, not generated. That leaves only two configuration files, namely /etc/default/grub and /boot/grub/custom.cfg. That seems sensible to me: the first one controls the auto-generated grub entries, the second one contains the hand-written ones. And it's even easy to extend the code that auto-generates grub entries by dumping additional scripts in /etc/grub.d.

Fedora 16 to use Btrfs as its default filesystem

rahulsundaram — Mon, 13 Jun 2011 10:24:52 +0000

"Obviously they do need backups, but if they need backups _even more_ than they do elsewhere, something is horribly wrong."

So you agree that they need backups for all their important data. Since I never claimed that they need it more than anywhere else, we are in complete agreement.

Anyone who is using Btrfs as this point or in the near future is hardly likely to be a casual desktop user anyway. So I hardly see why we are so bothered about my single statement that everyone should have backups.

The following is a side point but you are assuming a lot. Nowhere did I claim nor imply that I am helping anyone setup backups. In fact, I do not and I played no part at all in them setting up backups. Maybe my experience is different but since I never said that this was the average end user experience, there is no need to argue about that or assume that. So far, I haven't seen any neutral data on how many average end users actually do backups. Your opinions don't count.

Fedora 16 to use Btrfs as its default filesystem

elanthis — Mon, 13 Jun 2011 09:54:39 +0000

Obviously they do need backups, but if they need backups _even more_ than they do elsewhere, something is horribly wrong.

Your friends and family and coworkers are not normal casual users, if for no other reason than because they know you. Your personal anecdotes are as utterly meaningless as mine or anyone else's. If you can't step back and look at the larger picture outside your personal bubble then you are going to continue being really out of touch with what regular computer users are like. You can't look at your Aunt Tillie and use that as a measure of what an average computer user is like; you have to look at someone else's Aunt Tillie who has no nephew who's a bad-ass programmer, and in fact no contact at all with anyone who's more knowledgeable about computers than a CompUSA salesman.

grub support?

cmccabe — Mon, 13 Jun 2011 08:22:26 +0000

Calling grub2 a "huge mess" is an exaggeration, for sure. I appreciate the work that everyone put in to clean up the code and add new functionality.

However... the grub->grub2 transition annoyed me in several ways. There were a lot of changes that just seemed gratuitous. Why did partitioning numbering change to start at 1 rather than 0?

With the old grub, I only had to edit one config file, /boot/grub/grub.conf. My changes took effect immediately after editing this file. That was touted as one of the big benefits of grub over lilo-- with lilo, you had to re-run lilo every time you edited the lilo.conf. But now, I have to re-run update-grub every time I edit the grub2 configuration files.

Also, the number of configuration files for grub2 seems excessive. I only need one file to configure sshd, but just passing control to the kernel is now so complex that it needs an entire directory worth of shell scripts-- some of which are generated by other shell scripts?

Recently I installed Slackware 13 on an old laptop. I was a little bit surprised to find out that it still uses LILO as its bootloader. But, it works just fine.

I'm curious if anyone reading this has found a use for the extra modularity and extensibility of grub2? I'm just honestly curious. I know distributions like to implement nice looking startup screens for their installers, but that happens in the initramfs, not in the bootloader. And lilo supports background images and themes, too. So what am I missing?

Fedora 16 to use Btrfs as its default filesystem

rahulsundaram — Mon, 13 Jun 2011 07:51:24 +0000

I don't about your experiences but as I already noted, I know many casual desktop users (not developers) who do regularly take backups because they have lost data in the past and they cannot afford to do so again. This has nothing to do with the stability of the filesystem but often just physical hardware failures, viruses, accidental deletion of data and so on.

My point remains, everyone should have backups for their important data. It seems you fully agree with that and you are talking about implementation details like whether it should be automated and where the data should be stored. Anything that makes backup easier is fine by me.

LVM and rescuing systems

epa — Mon, 13 Jun 2011 07:22:10 +0000

So a typical consumer-grade motherboard lets you plug in new SATA devices to its SATA sockets while things are running? I never dared to try.

Fedora 16 to use Btrfs as its default filesystem

elanthis — Mon, 13 Jun 2011 07:04:19 +0000

If you think that personal backup solutions are used by anyone outside of a shockingly tiny minority of people, you are entirely out of touch with what the average computer user is like, does with his computer, knows about computers, thinks about computers, or wants to know about computers.

This is _really_ hard for computer nerds to accept -- especially so for developer-focused FOSS types whose circle of friends is mostly other developers -- but the regular user doesn't know what a backup is at anything more than a vague conceptual level, and he doesn't care because his computer is just a tool to get stuff done and learning computer terminology or programs or shortcuts is boring as crap and a waste of his time. Just like most FOSS developers probably couldn't tell the difference between a carburetor and a fuel injector without Googling them, most "casual users" can't tell the difference between a program and a document. Not because they're stupid, but just because they flat out don't freaking care, and would much much much rather spend their time out with friends or family, or outside, or watching TV, or playing games, or hitting the bar, or getting laid (as JWZ famously put it in his Groupware Bad article).

This is part of the reason why the OSes and platforms that target _real_ casual users remove the need for backups in the first place, by relying on either automatic or forced synchronization to other devices as often as possible or by syncing all documents and settings to "the Cloud." In other words, the backup always happens and is so ingrained into the system's use model that the user doesn't even need to be aware that it's happening.

When we get back into the realm of the scary/annoying/complicated desktop OS systems (be it Windows, OS X, Linux, or anything else), the only thing that saves the user from his own low give-a-crap meter is the expectation that the system will not randomly lose all his data because the vendor couldn't be bothered to make it stable enough for casual use.

I mean, seriously, we live in a world where a great number of "casual users" pay Apple or Best Buy a not-inconsiderable chunk of money to transfer files to new computers or recover files from fubar'd OS installs because the very act of copying files from one disk to another is not in their repertoire of computer skills. Or to look at it another way, we live in a world where anti-virus is pre-installed on 99% of Windows PCs because an overwhelming number of "casual users" (many of them self-proclaimed tech experts due to their frequent reading of PC Magazine and pcworld.com) still think that clicking Yes when the dialog "Naked_Hot_Actress_Screensaver.exe is from an untrusted source, are you sure you want to run this application?" pops up is a good idea.

Fedora 16 to use Btrfs as its default filesystem

Hausvib6 — Mon, 13 Jun 2011 03:27:25 +0000

They are just lazy, like me, or clueless. When the disaster strikes, they will running around screaming blaming the fs developers and/or everyone developing the stacks:
"ext4fs sucks"
"btrfs is still experimental, how dare you make it as my default fs!"
"linux ate my data"
etc.

Fedora 16 to use Btrfs as its default filesystem

cowsandmilk — Mon, 13 Jun 2011 02:14:27 +0000

Most normal users can afford backups more than they can afford to lose the stuff they are backing up.

Fedora 16 to use Btrfs as its default filesystem

ricwheeler — Mon, 13 Jun 2011 01:28:12 +0000

Do you have real numbers about what exactly went slow? With and without LVM?

No reason for it is have *any* impact unless something was misconfigured...

grub support?

mjg59 — Sun, 12 Jun 2011 22:02:40 +0000

grub leagcy about average open source code quality

Yeah, not really.

grub support?

cyperpunks — Sun, 12 Jun 2011 21:44:00 +0000

grub leagcy about average open source code quality, however with "huge mess" I don't talk about source code quality, it's the config system.
legacy grub as *one* simple config. grub2 has such complicated config file that a script is needed to create it. That's a big step forward in the correct direction...

Fedora 16 to use Btrfs as its default filesystem

tzafrir — Sun, 12 Jun 2011 20:23:26 +0000

Right. But then some bits are flipped on the hard-disk and your BTRFS is in a mess. You can't read your hourly snapshots. A simple btrfsck would have fixed that, right?

Fedora 16 to use Btrfs as its default filesystem

rahulsundaram — Sun, 12 Jun 2011 16:23:22 +0000

What is your definition of "normal user" exactly? Casual desktop users can and do retain good backups just fine. This is not just on Linux but Windows and Macs too. They all include personal backup systems which are popular. Storage is now more accessible than ever. If you can't afford to have good backups, maybe you can afford to lose all your data instead. Even if you can trust your filesystem 100%, hard disks can and do fail not to mention accidental deletion which is even more common.