Hello, Long time lurker, first time poster, hope I get things right.
I have an AuFS mount that is 21TB in size. I’m trying to use AuFS in a way that will ensure my disks (branches) do not fill up and result in out of space issues (preferably without using create=mfs). There are currently 7 disks, and I’m attempting to use the pmfsrr mode without much success. Here is a list of my disks: /dev/sde1 3.6T 3.4T 51G 99% /media/disks/WD-WCC4E5AFUJZK /dev/sdf1 2.7T 2.6T 36G 99% /media/disks/WD-WMC4N0765691 /dev/sdg1 1.8T 1.8T 35G 99% /media/disks/WD-WMAY00153458 /dev/sdh1 1.8T 528G 1.2T 31% /media/disks/WD-WMAZA4509546 /dev/sdi1 2.7T 2.6T 32G 99% /media/disks/WD-WMC4N0751110 /dev/sdj1 2.7T 2.6T 34G 99% /media/disks/WD-WMC4N0855507 /dev/sdk1 2.7T 2.6T 37G 99% /media/disks/WD-WCC1T1479153 /dev/sdl1 2.7T 2.6T 35G 99% /media/disks/SG-W1F1Q1J4 Here is my mount command (I’m running the latest build): mount -t aufs -o br:/media/disks/WD-WMC4N0765691=rw:/media/disks/WD-WMAY00153458=rw:/media/di sks/WD-WCC4E5AFUJZK=rw:/media/disks/SG-W1F1Q1J4=rw:/media/disks/WD-WCC1T1479 153=rw:/media/disks/WD-WMC4N0751110=rw:/media/disks/WD-WMC4N0855507=rw:/medi a/disks/WD-WMAZA4509546=rw-osum,create=pmfsrr:53687091200,udba=notifynone /mnt/media Now, from my understanding of the manual, the way I’m mounting with pmfsrr, I am setting a [low] value of 50GB. Again, according to my understanding, if all branches are below the “low” value, it will just round robin to one of the other branches that has the most space (from man: If there are less than ’low’ bytes available on all branches where the parent dir exists, aufs selects the one which has the most free space regardless the parent dir). The way I’m interpreting that is if “parentdir” exists on 2 of the branches, but both those branches are below the “low” value, it will go and select the branch with has the most free space, even if the parentdir does not exist, including another branch where the parentdir does not exist. Here’s where I’m running into the issue: 1. Copy 2GB file to /mnt/media/music/artist/file.mp4 2. the “parentdir” /music/artist exists on 2 of the branches that fall below the low level (WD-WMC4N0751110 and WD-WMC4N0855507, both around 32-34GB left) 3. The file does not get copied to WD-WMAZA4509546 (which has 1.2TB left), but instead WD-WMC4N0855507, which is the branch where the parentdir exists that contains the most free space (out of the two). My understanding should be that seeing as both disks fall below the “low” marker, the file should be copied to the branch with 1.2TB left, regardless if the parentdir exists on that branch. It is fully possible that I am misinterpreting the manual. If I mount with mfs, all writes go to the 1.2TB disk as expected. However, I am trying to avoid using mfs because I’d like to reduce fragmentation of the files across branches (where pmfsrr comes in), but still avoid the dreaded “out of space” error that will surely happen if I continue to use pmfsrr. The other reason I’m not a big fan of mfs is that if you have 2x3TB drives, they will “ping pong” (copying one file one place, one file another, I usually deal with 2-25GB files) with each other, which isn’t ideal. Can someone shed some light on this? I’ve been able to easily recreate my situation in my test environment and I can confirm that if the parentdir does not exist on a branch with pmfsrr, it will not copy a file to that branch (which would include creating the directory structure up to the point where the file is to be copied). Many thanks! J.
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