Thanks, Charles!<div><br></div><div>So, if we run out of available space, I&#39;ll get an error when I try to write to the hole? That should be OK... Very neat.</div><div><br></div><div>I think I know what my real problem is. I write the expected file size to the file header. This enables me to recover from a failed queue expansion: <a href="https://github.com/square/retrofit/blob/master/modules/android/src/retrofit/io/QueueFile.java">https://github.com/square/retrofit/blob/master/modules/android/src/retrofit/io/QueueFile.java</a></div>

<div><br></div><div>In the case I&#39;m investigating, the header says 16k, but the file size is only 4k.</div><div><br></div><div>I used &quot;rwd&quot; mode which syncs data by not metadata writes. In other words, it uses fdatasync() instead of fsync(). I think the file size qualifies as metadata. It sounds like my header write synced to storage but the file size metadata didn&#39;t, even though it was written first.</div>

<div><br></div><div>If I turn on metadata syncing, ftruncate() should sync, and everything should be OK.</div><div><br></div><div>Sound plausible? </div><div><br></div><div>Thanks,</div><div>Bob</div><div><br></div>