On Wed, Oct 6, 2021 at 3:37 PM Laurence Perkins <lperk...@openeye.net> wrote: > I think what to look for there would be if there's a way to align the BTRFS > chunks to the SMR blocks.
There are definitely ways to implement filesystems that are more compatible with SMR. You basically want something like a log-based filesystem. A COW filesystem is actually a really good candidate as they don't do in-place writes ever, and all you need to do is defer block frees and garbage collect and so on to make it more log-based. One of the issues though is that these drives obfuscate how they work. The filesystem has no way to intentionally write to the CMR vs SMR regions. This is why drive-managed SMR really shouldn't be a thing. Host-managed SMR makes a LOT more sense, because then the filesystem can mitigate most of the issues and not end up fighting the drive firmware, whose behavior isn't even standardized. > But the manufacturers decided to continue manufacturing CBR disks for the > surveillance industry, so I haven't had to worry about it just yet. There are lots of CMR drives out there. It is just that you have to be careful as nothing is well-documented and it is all subject to change. It is like trying to figure out how many channels a DIMM has or what its timing capabilities are. I saw a good price on an Exos drive and I believe those are all CMR. This is why I use slickdeals - you can set up searches and get alerts when a price drops. It also picks up stuff like Best Buy who often has some of the best prices on USB enclosures for whatever reason when they go on sale. -- Rich
