Hello All, For a Operating Systems project my partner and I are investigating ZFS' on disk layout for files and how it maintains full-stripe writes for RAIDZ. During our investigation, we have noticed that the hex pattern 0xFC42 is being written all over the disk and in large chunks. It seems to be written when files are accessed or even during idle periods. It also appears both in regular ZFS mirros as well as RAIDZ pools. The writes of this pattern are not contained any one area of the disk either. We have tried to think of what kind of data would be written in this manner and have come up blank.
We thought this pattern may be related to checksums and so we tried removing all the 20,000 or so FC42 patterns from a disk (we are using file backing stores). We then scrubbed the pool and we got only 28 checksum errors. When we again looked at the backing store, only about a quarter of the FC42 pattern returned. Does anyone recognize this pattern and explain why this is being written to the disk? Thanks, Brian and Kynan -- This messages posted from opensolaris.org
