Ian> I've been looking for a "simple" way to manage dm-cache devices Ian> for a while now -- something that operates a bit more like bcache Ian> than LVM cache does, while still using the dm-cache Ian> infrastructure. Having not found anything, I finally created Ian> "zodcache". (The name is mostly due to wanting something that Ian> could be used as a magic number -- 20DCAC8E.) Ian> Hopefully the README does a decent job of explaining how it works, so I Ian> won't belabor it here: I just read this over because I've just deployed lvmcache on my home system, and I was interested in how this would be different. One thing I would comment on is that having a diagram comparting the three options would be really useful. >From my reading of the docs, it's clear that zodcache is lower down the stack than LVMcache, but higher than bcache. For my setup, I have a pair of mirrored SSDs for root, /boot and lvmcache partitions. I'm using MD to mirror the partitions I've created on the SSDs. I then have another MD mirror composed of two 4Tb disks, which is turned into a PV in a VG with a bunch of LVs which are now cached. Before I had seperate VGs for some of my data, but now I've coalesced them so that I don't need multiple MD arrays for seperate cache PVs in each VG. So describinng how your setup can provide a central cache pool across multiple VGs would be awesome, but it's not quite clear to me that you can do this in reality without doing multiple layers of block devices. And since I'm paranoid (to a degree!) about resiliency, mirroring the cache devices is a critical part for me. Also, I'm on debian, so that's another piece of documentation that's kinda sorta missing. John -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
