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ZFS 2.3 released with ZFS raidz expansion

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Re: ZFS 2.3 released with ZFS raidz expansion

#11
post #10

Earlier quoted context omitted.

Is this possible elsewhere (re: other filesystems)?

Bcachefs allows it

Cool, just have to wait before it is stable enough for daily use of mission critical data. I am personally optimistic about bcachefs, but incredibly pessimistic about changing filesystems.

Re: ZFS 2.3 released with ZFS raidz expansion

#12
post #8

Earlier quoted context omitted.

Is this possible elsewhere (re: other filesystems)?

It is possible with windows storage space (remove drive from a pool) and mdadm/lvm (remove disk from a RAID array, remove volume from lvm), which to me are the two major alternatives. Don't know about unraid.

IIUC the ask (I have a hard time wrapping my head around zfs vernacular), btrfs allows this at least in some cases.

If you can convince btrfs balance to not use the dev to remove it will simply rebalance data to the other devs and then you can btrfs device remove.

Re: ZFS 2.3 released with ZFS raidz expansion

#13
post #8

Earlier quoted context omitted.

It is possible with windows storage space (remove drive from a pool) and mdadm/lvm (remove disk from a RAID array, remove volume from lvm), which to me are the two major alternatives. Don't know about unraid.

> It is possible with windows storage space (remove drive from a pool) and mdadm/lvm (remove disk from a RAID array, remove volume from lvm), which to me are the two major alternatives. Don't know about unraid. Perhaps I am misunderstanding you, but you can offline and remove drives from a ZFS pool. Do you mean WSS and mdadm/lvm will allow an automatic live rebalance and then reconfigure the drive topology?

So for instance I have a ZFS pool with 3 HDD data vdevs, and 2 SSD special vdevs. I want to convert the two SSD vdevs into a single one (or possibly remove one of them). From what I read the only way to do that is to destroy the entire pool and recreate it (it's in a server in a datacentre, don't want to reupload that much data).

In windows, you can set a disk for removal, and as long as the other disks have enough space and are compatible with the virtual disks (eg you need at least 5 disks if you have parity with number of columns=5), it will rebalance the blocks onto the other disks until you can safely remove the disk. If you use thin provisioning, you can also change your mind about the settings of a virtual disk, create a new one on the same pool, and move the data from one to the other.

Mdadm/lvm will do the same albeit with more of a pain in the arse as RAID requires to resilver not just the occupied space but also the free space so takes a lot more time and IO than it should.

It's one of my beef with ZFS, there are lots of no return decisions. That and I ran into some race conditions with loading a ZFS array on boot with nvme drives on ubuntu. They seem to not be ready, resulting in randomly degraded arrays. Fixed by loading the pool with a delay.

Re: ZFS 2.3 released with ZFS raidz expansion

#14
post #7

This is huge news for ZFS users (probably mostly those in the hobbyist/home use space, but still). raidz expansion has been one of the most requested features for years.

I'm not yet familiar with zfs and couldn't find it in the release note: Does expansion only works with disk of the same size? Or is adding are bigger/smaller disks possible or do all disk need to have the same size?

Re: ZFS 2.3 released with ZFS raidz expansion

#15
post #14
post #7

This is huge news for ZFS users (probably mostly those in the hobbyist/home use space, but still). raidz expansion has been one of the most requested features for years.

I'm not yet familiar with zfs and couldn't find it in the release note: Does expansion only works with disk of the same size? Or is adding are bigger/smaller disks possible or do all disk need to have the same size?

As far as I understand, ZFS doesn't work at all with disks of differing sizes (in the same array). So if you try it, it just finds the size of the smallest disk, and uses that for all disks. So if you put an 8TB drive in an array with a bunch of 10TB drives, they'll all be treated as 8TB drives, and the extra 2TB will be ignored on those disks.

However, if you replace the smallest disk with a new, larger drive, and resilver, then it'll now use the new smallest disk as the baseline, and use that extra space on the other drives.

(Someone please correct me if I'm wrong.)

Re: ZFS 2.3 released with ZFS raidz expansion

#16
post #8

Earlier quoted context omitted.

It is possible with windows storage space (remove drive from a pool) and mdadm/lvm (remove disk from a RAID array, remove volume from lvm), which to me are the two major alternatives. Don't know about unraid.

> It is possible with windows storage space (remove drive from a pool) and mdadm/lvm (remove disk from a RAID array, remove volume from lvm), which to me are the two major alternatives. Don't know about unraid. Perhaps I am misunderstanding you, but you can offline and remove drives from a ZFS pool. Do you mean WSS and mdadm/lvm will allow an automatic live rebalance and then reconfigure the drive topology?

> Do you mean WSS and mdadm/lvm will allow an automatic live rebalance and then reconfigure of the drive topo?

mdadm can convert RAID-5 to a larger or smaller RAID-5, RAID-6 to a larger or smaller RAID-6, RAID-5 to RAID-6 or the other way around, RAID-0 to a degraded RAID-5, and many other fairly reasonable operations, while the array is online, resistant to power loss and the likes.

I wrote the first version of this md code in 2005 (against kernel 2.6.13), and Neil Brown rewrote and mainlined it at some point in 2006. ZFS is… a bit late to the party.

Re: ZFS 2.3 released with ZFS raidz expansion

#17
post #14
post #7

This is huge news for ZFS users (probably mostly those in the hobbyist/home use space, but still). raidz expansion has been one of the most requested features for years.

I'm not yet familiar with zfs and couldn't find it in the release note: Does expansion only works with disk of the same size? Or is adding are bigger/smaller disks possible or do all disk need to have the same size?

IIRC, you could always replace drives in a raidset with larger devices. When the last drive is replaced, then the new space is recognized.

This new operation seems somewhat more sophisticated.

Re: ZFS 2.3 released with ZFS raidz expansion

#18
post #14
post #7

This is huge news for ZFS users (probably mostly those in the hobbyist/home use space, but still). raidz expansion has been one of the most requested features for years.

I'm not yet familiar with zfs and couldn't find it in the release note: Does expansion only works with disk of the same size? Or is adding are bigger/smaller disks possible or do all disk need to have the same size?

You need to buy the same exact drive with the same capacity and speed. Your raidz vdev be as small and as slow as your smallest and slowest drive.

btrfs and the new bcachefs can do RAID with mixed drives, but I can’t trust either of them with my data yet.

Re: ZFS 2.3 released with ZFS raidz expansion

#20
post #6
post #2

After years in the making ZFS raidz expansaion is finally here. Major features added in release: - RAIDZ Expansion: Add new devices to an existing RAIDZ pool, increasing storage capacity without downtime. - Fast Dedup: A major performance upgrade to the original OpenZFS deduplication functionality. - Direct IO: Allows bypassing the ARC for reads/writes, improving performance in scenarios like NVMe devices where cachi…

The first 4 seem like really big deals.

The fifth is also, once you consider non-ascii names.
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