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Is ZFS still incapable of enlarging/extending a filesystem by adding new disks to it without rebuilding the whole FS infrastructure?

by zmix 8y ago

snuxoll 8y ago
You’re confusing the expansion of a ZFS pool with the expansion of a RAID-Z vdev. Throwing new disks into a pool has always been possible, adding them to an existing RAID-Z vdev isn’t (yet, block pointer rewrite and RAID-Z expansion are coming). I run exclusively with mirrored vdev’s and have never run into issues growing my pool.
- Wowfunhappy 8y ago
  Is block pointer rewrite actually coming? It seems like it has been stalled for years and years...
  - snuxoll 8y ago
    There was just a talk on it this year, it’s coming but between the time it takes to go stable in OpenZFS and the time it takes to hit downstream (FreeBSD, ZoL) it might not be for a while yet.
aidenn0 8y ago
It's been able to do online enlarge and extend forever, and it will even automatically enlarge if you replace disks in a vdev one at a time allowing for resilvering. Perhaps you're thinking of shrinking, which it still cannot do without rebuilding the whole FS infrastructure.
cookiecaper 8y ago
While I definitely sympathize with the desire here, mirrored disks are almost always the best way to go. It has saved my butt just in my home setup a couple of times, most recently when a power connector got loose and started shutting a disk on and off basically at random. Mirrored disk mean quick recovery from such scenarios and relatively-limited impact during degradation. My opinion after trying both parity-checked redundancy and true mirrored redundancy is that any serious data storage should be strictly on mirrored volumes (preferably with disks of substantially different ages so you don't risk them dying within a couple weeks of each other, possibly before a replacement gets installed). I once read "50% storage efficiency is plenty, don't be greedy". Although painful for the home user, that seems like the right attitude to take for important stuff, especially as volume sizes increase. It can be a very slow and very fraught process to recover several TBs from parity data.
zmix 8y ago
Why the downvotes?

Is ZFS still incapable of enlarging/extending a filesystem by adding new disks to it without rebuilding the whole FS infrastructure?

by zmix 8y ago

Is ZFS still incapable of enlarging/extending a filesystem by adding new disks to it without rebuilding the whole FS infrastructure?

snuxoll 8y ago

You’re confusing the expansion of a ZFS pool with the expansion of a RAID-Z vdev. Throwing new disks into a pool has always been possible, adding them to an existing RAID-Z vdev isn’t (yet, block pointer rewrite and RAID-Z expansion are coming). I run exclusively with mirrored vdev’s and have never run into issues growing my pool.

Wowfunhappy 8y ago
Is block pointer rewrite actually coming? It seems like it has been stalled for years and years...
- snuxoll 8y ago
  There was just a talk on it this year, it’s coming but between the time it takes to go stable in OpenZFS and the time it takes to hit downstream (FreeBSD, ZoL) it might not be for a while yet.

aidenn0 8y ago

It's been able to do online enlarge and extend forever, and it will even automatically enlarge if you replace disks in a vdev one at a time allowing for resilvering. Perhaps you're thinking of shrinking, which it still cannot do without rebuilding the whole FS infrastructure.

cookiecaper 8y ago

While I definitely sympathize with the desire here, mirrored disks are almost always the best way to go. It has saved my butt just in my home setup a couple of times, most recently when a power connector got loose and started shutting a disk on and off basically at random. Mirrored disk mean quick recovery from such scenarios and relatively-limited impact during degradation. My opinion after trying both parity-checked redundancy and true mirrored redundancy is that any serious data storage should be strictly on mirrored volumes (preferably with disks of substantially different ages so you don't risk them dying within a couple weeks of each other, possibly before a replacement gets installed). I once read "50% storage efficiency is plenty, don't be greedy". Although painful for the home user, that seems like the right attitude to take for important stuff, especially as volume sizes increase. It can be a very slow and very fraught process to recover several TBs from parity data.

zmix 8y ago

Why the downvotes?