Handle Hardlinks

[nickdemise]

Hi all,

I would like to discuss, and expand my knowledge, about potentially enhancing the script to handle hardlinks, rather than simply ignoring them.

In #22 johnpyp mentions "(data) can't be trivially un-hardlinked after without knowledge of which path is in the "balance target" vdev."
I don't quite understand this, could you please expand? Lets say we don't know the path of the balance target vdev and pick a path at random, in the end would it not average out ?

Lets say i have 2vdevs, and they are 60% populated, with files that each have one or more hardlinks, which is balanced 50-50 data usage.
I now add a new empty equal size vdev to the pool and wish to rebalance.

We look at file_1, its got two hardlinks (50%-50%-0)
Could i copy file_1 --> file_1_tmp
Delete the two hardlinks & file_1
Create two new hardlinks to file_1_tmp
Rename file_1_tmp

What does the end data result look like? (15%-15%-70% or so?)

I understand i could be quite naive/crude in this approach, but wish to understand and hope to resolve this, as i'm sure alot of people with similar *arr media setups would appreciate such a feature.

Thanks,
NickyD

[Xaelias]

I'm curious too because that sounds like a solvable problem. I'm also a bit confused by

without knowledge of which path is in the "balance target" vdev."

We know which path is which. My understanding is that this script keeps track of everything that was processed or not and we just created a copy of the file.

[nickdemise]

did anyone have any thoughts/comments on if this would be doable ?

[hbilbo]

See #46

[nickdemise]

See #46

Cheers mate i'll go through it in more detail, but just quickly, does this only work for files with precicely 2 hardlinks ?

[hbilbo]

Yes it specifically checks if the file has 2 hardlinks and only processes those. I don't have a use case for anything more than that but you could pretty easily modify the script to handle files with 3 hardlinks if that was a legitimate use case.