Hi Mark, On Mon, 2012-06-25 at 18:11 -0700, Mark Trumpold wrote: > Hello, > > I have a configuration where I use qemu/qcow loop filesystems > on top a nilfs filesystem to yield writeable snapshots. > > The symptom I see is the nilfs filesystem "ballooning" in size when > writing large chunks of data to the qcow loop filesystem. I also see > _many_ nilfs checkpoints with small "NBLKINC" counts (>20 <50). > > My working theory is nilfs creates checkpoints for each synchronous > write, and qcow insists on writing synchronously, thus the ballooning > of checkpoints. I can cite man page for NILFS2: "When data is written or any change is made to a NILFS2 file system, it automatically creates a checkpoint. A checkpoint represents a consistent state of the NILFS2 file system of a certain instant.". > > One question is would it be possible to have nilfs not checkpoint so > often. I've tried the 'nilfs-tune -i ..' to no avail - apparently > synchronous writes overrule this setting. As you can see, checkpoint is a base technique of NILFS2 functioning. But you can manipulate by checkpoints during NILFS2 functioning by means of nilfs-cleanerd daemon. Do you use nilfs-cleanerd daemon? Please, read man page for nilfs-cleanerd daemon and its configuration file. I can cite man page: "nilfs_cleanerd is a system daemon which reclaims disk space of NILFS2 file system found in device." With the best regards, Vyacheslav Dubeyko. -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
