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ZFS Hits an Important Milestone, Version 0.6.1 Released
sfcrazy writes "ZFS on Linux has reached what Brian Behlendorf calls an important milestone with the official 0.6.1 release. Version 0.6.1 not only brings the usual bug fixes but also introduces a new property called 'snapdev.' Brian explains, 'The snapdev property was introduced to control the visibility of zvol snapshot devices and may be set to either visible or hidden. When set to hidden, which is the default, zvol snapshot devices will not be created under /dev/. To gain access to these devices the property must be set to visible. This behavior is analogous to the existing snapdir property.'"
Sorry, but the title is misleading. ZFS did not hit 0.6.1, only this port for Linux. ZFS uses it's own versioning, which actually recently bumped to v5000.
And this "FFS", this is also a file system? ( :P )
And this "FFS", this is also a file system? ( :P )
Yes.
Version 5000 is used for community ZFS implementations that have feature flags (Illumos, BSD, and Linux).
If you're talking about Solaris, the current version is 34; any version past 28 comes after Oracle closed off Solaris. Note that beyond version 28, the community and Oracle ZFS pools are not interoperable.
Oh, no! You have walked into the slavering fangs of a lurking grue!
Better data integrity? Checksums on all blocks means the OS can tell if data is corrupt, and the data can be seamlessly recovered from redundancy (typically parity from raidz or raidz2, which also doesn't have the raid5 write hole because ZFS is copy-on-write).
Easier to use? zfs management happens through the "zfs" and "zpool" commands which are generally much easier to work with than obscure necromancy commands required for traditional types of systems that make me care about cylinders and partitions.
More flexible? The storage pool method, where you build a pool of capacity and allocate filesystems out of it, gives you a great deal of flexibility and simplicity. I just keep adding more storage to my pool as required, either by adding more RAID arrays or increasing the size of disks in those arrays, and then I've got my primary filesystem for storage, I've got a deduplicated one I use for backups, and I've got a compressed one I use for long-term archives. And creating a new one like that takes about five seconds without having to repartition or reformat anything. Creating/deleting filesystems is about as much effort as creating/deleting files.
Easier snapshots? Snapshots are instant on copy-on-write filesystems. Any modification of data causes the block to be copied anyhow, so all a snapshot has to do is not delete older blocks.
ZFS is one of a handful of next-gen filesystems (along with BTRFS and HAMMER) that are so far beyond traditional filesystems that it's a really eye-opening experience using them. That's not to say ZFS is perfect, or that the ZFSonLinux implementation is perfect, but it's in a reasonable state of stability at this point, and the advantages that these new filesystems offer is substantial.
I do wish that ZFS had asynchronous deduplication like HAMMER, though. ZFS deduplication requires atrocious amounts of RAM (estimates go from 5 to 20 gigabytes of RAM per terabyte of deduplicated data), while HAMMER has effectively no extra memory required at runtime for dedupe, because it just scans the disk afterwards and does the deduplication after the fact, so it doesn't need to hold the full block table in memory at all times.