On Wed, Jan 9, 2019 at 6:16 AM james harvey <jamespharve...@gmail.com> wrote: > ... > Not in the logs, but I ran more tests modifying the error message to > include discard_granularity and vol->cluster_size. On a thin volume, > 65536 and 4096. On a thick volume, 512 and 4096. > ...
P.S. LVM thin volumes have a chunk size - see https://www.systutorials.com/docs/linux/man/7-lvmthin/#lbBC That's the smallest size that's actually allocated within the thin pool, and I believe has an inverse relationship to the size of the LVM metadata keeping track of it all. LVM thin chunk sizes must be multiples of 64KiB, a minimum of 64KiB, and a maximum of 1GiB. Optimizing for thin provisioning rather than snapshots, larger values perform better. On this machine, I'm using the default 64KiB chunk size, but on other machines, I certainly use larger. Additionally, what I'm doing (in my real scenario rather than the recent tests) is making a LVM thin volume that I'm giving the VM as its own raw disk. So, internally, there's the partition table. So, if groups of consecutive clusters all being empty were looked for, to make up an entire discard_granularity, and if so, discarding those, the alignment would presumably need to be considered from the beginning of the underlying device (the LVM thin volume), rather than just within the partition. _______________________________________________ ntfs-3g-devel mailing list ntfs-3g-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ntfs-3g-devel
