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by KozmoNau7 1874 days ago
With btrfs, you can add one or however many new devices you want to a storage pool, then rebalance to ensure redundancy across the whole pool. If the device you add is already btrfs formatted, its contents get added to the storage pool, rather than requiring a reformat.

It really surprises me that zfs apparently cannot do this.

The main reason I use btrfs is the flexibility. Subvolumes instead of partitions, and easy expandability. Storage should be dynamic, not static.
3 comments
kylegordon 1874 days ago
> It really surprises me that zfs apparently cannot do this.

Likewise. I really want to like ZFS, but with the 'buy twice the drives or risk your data' approach as above really deters me as a home user.

ZFS has been working on developing raidz expansion for a while now at https://github.com/openzfs/zfs/pull/8853 but I feel that it's a one-man task with no support from the overall project due to that prevailing attitude.

BTRFS is becoming more appealing, even though it has rough edges around RAID write holes that really isn't a big deal, and reporting of free space. I can see my home storage array going to BTRFS in the near future.

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rubenbe 1874 days ago
> The main reason I use btrfs is the flexibility. I agree, and I as a small home user, I really like the RAID using different sized disks. E.g. running a raid 1 on three disks: 2TB+4TB+6TB. It also offers the possibility to increase the storage size over time when drives fail by replacing them with a larger disk.
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fiddlerwoaroof 1874 days ago
They have dRAID, but last I checked RAID 5/6 is basically asking for data loss with modern drive sizes.
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kalleboo 1874 days ago
> last I checked RAID 5/6 is basically asking for data loss with modern drive sizes

This is a debate I would love to see with people who have experience. Since I've seen individuals speak with authority on both sides.

I get that if you have a basic array of disks humming along with a big-ass ext4 partition, once one drive dies, the risk of the other drives being riddled with errors is huge.

But what if your array is both (1) using ZFS or BTRFS (with data checksumming) and (2) has scheduled full-disk data scrubs once a month or so? Wouldn't you catch the initial recoverable errors quick enough?

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jjav 1873 days ago
> Wouldn't you catch the initial recoverable errors quick enough?

Not always no.

I've had drives reporting failures for months that zfs scrub keeps fixing, tons of time to get a spare.

But drives also fail suddenly with no history of zfs or SMART errors.

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