Approved: Fedora 33 Desktop Variants Defaulting To Btrfs File-System

[k1e0x]

I'm probably just a noob and used the wrong name. I just added the ZFS pool to libvirt (as raw zfs pool so it's using it like it would for LVM, it's not just a filesystem with virtual disk files in it), it created the VM disks on its own, so if it's doing ZVOLs by default I'm using zvols.
Plus a couple SSDs for "log" (in mirror) and "cache".


Yeah, most people think it's some magic thing that will shrink their data, but it's good only if you have A LOT of duplicated data and that's uncommon. Trasparent compression is what most people can benefit for.

Yeah, it seems like the UI was written to just give it full pool control, (with zvols). ..and in a lot of cases that would be fine but if you want to nest it in a dataset (say pool/kvm) you need to use the work around I mentioned.

Also an oddity about libvirt, it supports bhyve as a hypervisor. tho poorly. Would be cool to see this fixed.

[AdamW]

Whoo boy, this thread sure is...something.

So just to comment on a few things:

1. This is very much a Fedora decision. You know how we keep saying that Fedora isn't just a beta for RHEL? Well...consider this as Exhibit A. This isn't happening in Fedora because it's going to happen in RHEL 9 next. It's happening in Fedora because some people very definitely wearing Fedora hats wanted it to happen in Fedora, and convinced FESCo that it should. (Also note that there is an element of experiment about this Change: it's landing on the explicit understanding that we might decide, in a few days or weeks or months, that it was a bad idea and we should change back.) It's not coming from the folks who set RHEL's storage strategy (take a look at the names on the Change proposal) and it does not tell you anything about changes to that storage strategy. On this topic - note that this Change is to the Fedora *Workstation* default. Fedora *Server*'s default remains xfs-on-LVM.

2. As the Change has landed *so far*, we are kinda intentionally not doing too much stuff to take advantage of btrfs' super shiny advanced features, broadly on the "learn to walk before you learn to run" principle. Just changing the default FS is a pretty major first step, and we want to shake that out thoroughly before we start piling more changes up on top of it. But we reserve the right to start pilin' away in future.

3. Can you folks stop calling each other morons please? Pretty please? Thanks!

[intelfx]

Deftragmentation is completly not needed.
ZFS uses SLAB allocator which prevents fragmentation.

Yeah, no. That's a complete and utter lie.

First, the only thing slab allocators do is they put a hard 50% low boundary on internal fragmentation (or, rather, internal utilization). Slab allocators do not guarantee anything else.

As for external fragmentation, slab allocators typically _worsen_ it. Imagine writing 128K of data in one write(), and then 64K more. With zfs, you are guaranteed to fragment at this boundary, because different slabs _will_ be used for 128K and 64K writes.

Also you get funny fireworks when your disk is almost full and there are no slabs left for your chosen block size. Read this thread backwards, someone has already mentioned the absolutely wondrous hack zfs had to do to fix this.

On Linux SLAB allocator is used in memory management. Did you heard that someone is doing "RAM defrgmentation" on Linux?

Everyone is doing RAM defragmentation on Linux.

Google "memory compaction", you will be surprised.

Works for user pages only, of course. Do you know the single most significant source of non-movable pages in Linux (also the reason why you generally can't allocate 1G hugepages post boot, or also the reason why stuff like CMA with boot-time memory reservation had to be invented for non-scatter-gather DMAs out there in the embedded hw)? You guessed right, slabs.

[k1e0x]

oracle owns oracle zfs, i.e. the original stable and enterprise-grade filesystem, not some noname garage production

You do know the guy that co-developed it at Sun still leads the development of OpenZFS. It's by in large the same people that wrote it originally.

The no-name garage group is the b-team Oracle had to hire after all the ZFS and Solaris engineers walked out on them.

You can learn about that exodus here. https://www.youtube.com/watch?v=-zRN7XLCRhc

if you were programmer, you would know that by porting filesystem to different os you don't get same filesystem, you get something completely different, which inherits neither speed nor correctness, that you'll have to build from scratch

What? no. What are you talking about? How old are you?

as i said, i don't care. license choice is the problem of code owner, and he has to live with it

The Sun developers chose the CDDL (actually they chose the Mozilla Public Licence) - Do you hate Firefox and LibreOffice now too? You do know Sun also wrote LibreOffice right? CDDL is almost identical. It is a weak copyleft licence that requires source code on the distribution of binarys. This is a good thing. Go read it, you won't find any "secret scary language" in it. It is not like the APPL that gives Apple control.

only distros who have nothing to lose

Careful.. you might not like living in a world where there was only one distro.. How much do you trust IBM?

owning most anti-linux card would be stupid, wouldn't it?

Again, seriously.. how old are you? This is childish. It's hardware and it does a job. Use it if you like. (Personally I tend to find AMD cards work well for me... but I wouldn't hate someone using or buying a computer with an Nvidia card in it. Honestly.. you are taking things a little strong here.)

[starshipeleven]

And I already wrot i that without keeping enough number of hashes of blocks in memory btrfs dedup is useless (is only technology demonstration).

Dunno, it still shrinks dramatically the space used, if the data can be deduped.
Also it's ONLINE even if it isn't done trasparently. OFFLINE means that the filesystem is unmounted, not even crap like NTFS needs to be unmounted to be deduplicated (on servers where you can actually deduplicate it)

btrfs is not usinfg SLAB allocator and this is why it needs and can be defragmented.

All CoW filesystems can become fragmented if large files are edited constantly (like VMs and databases). SLAB isn't magic. I'm not talking of NTFS level of bullshit instant-fragmentation, but will still eventually happen.

Btrfs has at least autodefrag, so it will automatically deal with it. Not that it matters much for databases or VMs because its performance with such workloads is complete garbage, but it's ok for anything else.

[pal666]

proper dedup domne online is able to lower write IOs

by lowering available memory(much more precious resource). it's not hard to implement, it's just not very useful, that's the only reason it's not implemented yet for btrfs. and it's called inband, online means "without unmount"

[pal666]

Just go out and play with it some, I'm sure you'll find a lot of the same features

it's hard to play with something which is unavailable and can't be resized

Use it on FreeBSD, it's in the kernel there.

i touch freebsd only when i'm paid to do it

You know ZFS send can do a delta copy of an encrypted dataset? Pretty cool. I think BTRFS still uses LUKS right?

integrated encryption and per-object raid levels are two large planned, but still missing features of btrfs

[pal666]

Wrong. ZFS even today does not have such thing becase it does not need it

imbecile, "such thing" was posted by you. zfs added multiple copies on single device in 2010, after btrfs had them. zfs is copying btrfs

[pal666]

btrfs is not usinfg SLAB allocator and this is why it needs and can be defragmented.

imbecile, it's a quote from zfs dev

One of the major problems with the ZFS approach - "slabs" of blocks of a particular size - is fragmentation

[starshipeleven]

Should try it the other way around. ZVOL's make excellent vm disks.

I'm probably just a noob and used the wrong name. I just added the ZFS pool to libvirt (as raw zfs pool so it's using it like it would for LVM, it's not just a filesystem with virtual disk files in it), it created the VM disks on its own, so if it's doing ZVOLs by default I'm using zvols.
Plus a couple SSDs for "log" (in mirror) and "cache".

there are some advantages to that (such as VM's) but it isn't what a lot of end users expect.

Yeah, most people think it's some magic thing that will shrink their data, but it's good only if you have A LOT of duplicated data and that's uncommon. Trasparent compression is what most people can benefit for.