On Tue, Oct 28, 2014 at 9:49 AM, Arne Jansen via illumos-zfs <[email protected]> wrote: > Funny enough just a few days ago we've been searching for a way to reserve > space > for individual files, just what posix_fallocate(3C) does. Unfortunately ZFS > doesn't seem to support this. > Our use case is to allow our customer to do chunked uploads coming out of > order. > As we don't want sparse files on our platform, posix_fallocate would be a very > easy way to allow customers to write at arbitrary offsets without creating > holes > in files. > So, I would be interested in this feature.
I agree that posix_fallocate(3) is a better interface than ioctl. >> Is the goal to reserve space for individual files, and doing so physically >> (as >> opposed to logically, like filesystem reservations) was the easiest way to >> implement it? Did you investigate implementing a logical per-file >> reservation? >> A logical reservation should perform better (both when setting the >> reservation, >> and when writing, since there would be more physical free space). I don't think physical reservation is necessary to honor the semantics. The basic goal is to ensure that writes to the file will never fail (at least, due to pool/filesystem being out of space) up to the file size specified. It's basically a more targeted version of the filesystem reservation property. --Will. _______________________________________________ developer mailing list [email protected] http://lists.open-zfs.org/mailman/listinfo/developer
