4 ms·

The filesystem as basic infrastructure has to be robust and fuss free. The complex stuff is going to be built on top of that. After years of btrfs I realized w

by throw2016 9y ago

The filesystem as basic infrastructure has to be robust and fuss free. The complex stuff is going to be built on top of that. After years of btrfs I realized while the all the features around snapshotting, send/receive etc are great the cost in performance and other issues is too high. And using plain old ext4 is more often than not the best compromise so you can forgot just about the fs and focus on higher layers.

StavrosK 9y ago
How do you do snapshots on ext4? Don't large datasets take forever?
- bubblethink 9y ago
  I don't think ext4 has native snapshots. You can use lvm-thin for snapshots. Note that lvm-thin is different from regular lvm snapshots, which are known to be inefficient. RHEL has decent support for this feature, and will even let you set it up in the GUI during installation.
  - StavrosK 9y ago
    That snapshots the entire volume, though, right? I don't want to waste time on snapshotting my movies when all I want is my family photos... It seems that the GP's point that the fs should just store files is rather debunked, as snapshots are an extremely useful feature for a filesystem.
    - simcop2387 9y ago
      lvm-thin snapshots the entire volume but in a more Copy-on-Write like way. https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_Administration/thinprovisioned_volumes.html https://access.redhat.com/documentation/en-US/Red_Hat_Enterp...
    - bubblethink 9y ago
      Yes snapshots are for volumes. There's also a yum plugin which will do before and after snapshots. Rhel and suse have this feature which works with lvm-thin as well as btrfs.
buster 9y ago
I came to say similar things. After having had problems with ZFS (on Solaris) and btrfs, but never on ext4 or other "simple" filesystems i am wondering if i need and want all that complexity in my filesystem: And no, i don't. Snapshots are nice, sure. But i'd rather do that on top of my filesystem (they're called backups) and leave the filesystem lean, simple, fast AND reliable. Every filesystem may have its own problems, but i feel that the "attack surface" of my filesystem should be as small as possible. Do i rather want to have a bug in my filesystem implementation concerning snapshots or would i rather have that bug in my backup tool? IMO, the FS should be rockstable and lean and not "cool and fancy". I can do fancy on top of rockstable.
c3833174 9y ago
The nice thing about btrfs vs ZFS is that you can just use it like a normal filesystem ignoring all the advanced features and still get the benefit of checksumming (plus duplicated metadata by default on spinning disks) and compression
- throw2016 9y ago
  The problem with btrfs and cow in general is poor performance for databases and overall, in some cases significantly, slower performance than ext4. ZFS has high memory requirements. If your use case mainly revolves around the benefits of snapshots then it definitely makes sense.

StavrosK 9y ago

How do you do snapshots on ext4? Don't large datasets take forever?

bubblethink 9y ago
I don't think ext4 has native snapshots. You can use lvm-thin for snapshots. Note that lvm-thin is different from regular lvm snapshots, which are known to be inefficient. RHEL has decent support for this feature, and will even let you set it up in the GUI during installation.
- StavrosK 9y ago
  That snapshots the entire volume, though, right? I don't want to waste time on snapshotting my movies when all I want is my family photos... It seems that the GP's point that the fs should just store files is rather debunked, as snapshots are an extremely useful feature for a filesystem.
  - simcop2387 9y ago
    lvm-thin snapshots the entire volume but in a more Copy-on-Write like way. https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_Administration/thinprovisioned_volumes.html https://access.redhat.com/documentation/en-US/Red_Hat_Enterp...
  - bubblethink 9y ago
    Yes snapshots are for volumes. There's also a yum plugin which will do before and after snapshots. Rhel and suse have this feature which works with lvm-thin as well as btrfs.

buster 9y ago

I came to say similar things. After having had problems with ZFS (on Solaris) and btrfs, but never on ext4 or other "simple" filesystems i am wondering if i need and want all that complexity in my filesystem: And no, i don't. Snapshots are nice, sure. But i'd rather do that on top of my filesystem (they're called backups) and leave the filesystem lean, simple, fast AND reliable. Every filesystem may have its own problems, but i feel that the "attack surface" of my filesystem should be as small as possible. Do i rather want to have a bug in my filesystem implementation concerning snapshots or would i rather have that bug in my backup tool? IMO, the FS should be rockstable and lean and not "cool and fancy". I can do fancy on top of rockstable.

c3833174 9y ago

The nice thing about btrfs vs ZFS is that you can just use it like a normal filesystem ignoring all the advanced features and still get the benefit of checksumming (plus duplicated metadata by default on spinning disks) and compression

throw2016 9y ago
The problem with btrfs and cow in general is poor performance for databases and overall, in some cases significantly, slower performance than ext4. ZFS has high memory requirements. If your use case mainly revolves around the benefits of snapshots then it definitely makes sense.