Arch Linux

Enverex

Member

From: UK

Registered: 2007-06-13

Posts: 159

Website

Re: Usable Union Filesystems?

I'm actually running into an issue with AUFS now and it seems there is no real documentation about most of the features anywhere. The official manpage is all that exists and it doesn't really -explain- half of the features enough for them to make any sense, unless you already know what it means. A bit of a catch 22.

Anyway, I'm currently using this:

store                   /mnt/store      aufs            nofail,sum,create=pmfs:3600,dirs=/mnt/WDCG2TB=rw:/mnt/WDCG2TB-2=rw:/mnt/HDS3TB=rw       0 0

What this should do is write to whichever drive has more space, assuming the folder you're referring to has the parent folder. For example, if both WDCG2TB and WDCG2TB-2 had a folder called TV and I wrote something to that folder, it should write the file(s) to whichever those two drives has more free space. HDS3TB doesn't contain a folder so it should be left alone.

This is all done because I'm using "pmfs" which is "parent most free space". So write to whichever drive contains the parent folder I'm writing to, and has the most free space.

BUT, I've been writing things to the TV folder, and it's been putting them into HDS3TB, which, until AUFS created it, didn't have a TV folder, so should have been ignored.

UGGGH. This is becoming incredibly annoying. This may be related to "Policies for Copy-Up" but their explanations in the man page honestly make little sense to me.

WindPower

Member

Registered: 2012-09-06

Posts: 12

Re: Usable Union Filesystems?

I'd like to be able to add and remove drives with little hassle, plus if one drive dies, I'd rather not lose everything, at least in this setup I only lose what's on the single drive, not all drives (Mirrored RAID isn't an option due to cost and the fact I would need far more drive bays than I have).

Just curious, why is RAID 5 not an option?

Enverex

Member

From: UK

Registered: 2007-06-13

Posts: 159

Website

Re: Usable Union Filesystems?

I'd like to be able to add and remove drives with little hassle, plus if one drive dies, I'd rather not lose everything, at least in this setup I only lose what's on the single drive, not all drives (Mirrored RAID isn't an option due to cost and the fact I would need far more drive bays than I have).

Just curious, why is RAID 5 not an option?

Because I may be adding or removing drives of any size at any time, would like the ability to pull data off a single drive should the worst happen and don't really have enough free space to afford the cost that redundancy would incur. That Wiki article also seems to list a lot of performance hits with RAID 5 too.