On 2023-09-15 2:07 p.m., Peter Boy wrote:
Am 15.09.2023 um 17:23 schrieb Bill Cunningham <bill.cu1...@gmail.com>:
WHat is the reason Peter behind xfs being used on the server edition
and btrfs on the workstation? I pretty much stick with ext3. I don't
even use ext4 really. I've never used xfs.
It is basically about data protection, performances, reliability and easy
administration
(seehttps://docs.fedoraproject.org/en-US/server-working-group/docs/server-technical-specification/)
So, the Fedora server editions (i.e. Server and CoreOS) use LVM/xfs.
And please, think twice when you read something like "BTRFS protects us from
"silent" corruption of files, which is more of an issue with large volumes of data“
or „... large organizations with many users, btrfs is expected to reduce problems with data
corruption…“. It’s more kind of marketing speech than any valid decision criteria or
technically based argument. If you use the search engine of your preference you will find a
lot of detailed and and technically based discussions of Fedora and Red Hat engineers about
the topic. As in most cases, there is no „one absolute truth“ about filesystems as many
missionaries claim again and again. It is a question of weighing and criteria for a use case
or also for a type of use cases.
Umm, no.
Fedora server uses LVM because that's what most people have upgraded
from. It adds another data layer to the i/o stack, increasing on-disk
complexity. It is normally required under XFS to provide the missing
pieces like RAID levels and snapshots, as XFS was designed in the 70s
with hardware RAID in use. Its also what most sysadmins were trained to
use, and its hard to change old habits. Its solid, but really old tech
that BTRFS and ZFS can almost always do better. Unlike LVM, RAID-5/6 is
currently a problem for BTRFS, as it has the write-hole bug that almost
all hardware and software implementations also have with the exception
of ZFS. Disks are really cheap, so 2 or 3-way mirroring or RAID-1 are
currently the ways to go on BTRFS. It should be noted that imho the
RAID-Z levels on ZFS are superior to all other solutions for reliable
data preservation and performance.
Fedora server uses XFS because that's what RHEL and therefore the
certified sysadmins use. Consumer disks are actually more reliable than
enterprise disks, but stall for very long periods when re-reading
failing sectors. So, BTRFS actually works better on enterprise disks,
as the stall is far smaller. It is probably the #3 or 4 filesystem
around for performance and reliability, but managing it is positively
arcane. There are a number of normal admin operations that are very
difficult using XFS, such as shrinking a filesystem (even by a couple of
sectors to use a replacement disk). It also does no runtime error
detection/correction of your data, so you depend upon RAID hardware or
LVM to do that for you. If you get an error detected during one of
these repair sweeps, recovery is usually no better than an uncorrectable
multi-bit BTRFS or ZFS failure. Putting XFS on a single disk is very
questionable as a result.
Fedora desktop uses BTRFS by default for a number of really good
reasons. BTRFS detects bit-rot on the fly. With mirrored or RAIDed
disks it can also correct that bit-rot on the fly. XFS cannot do that,
and requires weekly error detection work. Putting ZFS or BTRFS on RAID
hardware actually makes everything slower, as they do a better, faster
and more reliable job in software. BTRFS and ZFS also have many
operational advantages, like much faster migrations, near-instantaneous
snapshotting and rollback (LVM takes hours to do the same), and much
faster off-machine backups.
While ZFS is the gold standard for reliable filesystems, with the
exception of the Ubuntu and Oracle platforms, it cannot be used without
paying Oracle lots of money. BTRFS reimplements much of ZFS in a
legally unencumbered codebase. It is unclear why Fedora has not moved
server installs to BTRFS by default, as the advantages in complexity,
training and data reliability are huge. Those all make a BTRFS or ZFS
server cheaper to operate, sometimes by a considerable margin. I know
all the RHEL sysadmin people will come out of the woodwork and start
shouting about that statement, but just maybe they are incorrect. YMMV
of course.
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