Marc MERLIN posted on Fri, 29 Jun 2018 09:24:20 -0700 as excerpted: >> If instead of using a single BTRFS filesystem you used LVM volumes >> (maybe with Thin provisioning and monitoring of the volume group free >> space) for each of your servers to backup with one BTRFS filesystem per >> volume you would have less snapshots per filesystem and isolate >> problems in case of corruption. If you eventually decide to start from >> scratch again this might help a lot in your case. > > So, I already have problems due to too many block layers: > - raid 5 + ssd - bcache - dmcrypt - btrfs > > I get occasional deadlocks due to upper layers sending more data to the > lower layer (bcache) than it can process. I'm a bit warry of adding yet > another layer (LVM), but you're otherwise correct than keeping smaller > btrfs filesystems would help with performance and containing possible > damage. > > Has anyone actually done this? :) So I definitely use (and advocate!) the split-em-up strategy, and I use btrfs, but that's pretty much all the similarity we have. I'm all ssd, having left spinning rust behind. My strategy avoids unnecessary layers like lvm (tho crypt can arguably be necessary), preferring direct on-device (gpt) partitioning for simplicity of management and disaster recovery. And my backup and recovery strategy is an equally simple mkfs and full-filesystem-fileset copy to an identically sized filesystem, with backups easily bootable/mountable in place of the working copy if necessary, and multiple backups so if disaster takes out the backup I was writing at the same time as the working copy, I still have a backup to fall back to. So it's different enough I'm not sure how much my experience will help you. But I /can/ say the subdivision is nice, as it means I can keep my root filesystem read-only by default for reliability, my most-at-risk log filesystem tiny for near-instant scrub/balance/check, and my also at risk home small as well, with the big media files being on a different filesystem that's mostly read-only, so less at risk and needing less frequent backups. The tiny boot and large updates (distro repo, sources, ccache) are also separate, and mounted only for boot maintenance or updates. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
