Let me give a real life example of what I believe is a fragmented zfs pool.
Currently the pool is 2 terabytes in size (55% used) and is made of 4 san luns (512gb each). The pool has never gotten close to being full. We increase the size of the pool by adding 2 512gb luns about once a year or so. The pool has been divided into 7 filesystems. The pool is used for imap email data. The email system (cyrus) has approximately 80,000 accounts all located within the pool, evenly distributed between the filesystems. Each account has a directory associated with it. This directory is the users inbox. Additional mail folders are subdirectories. Mail is stored as individual files. We receive mail at a rate of 0-20MB/Second, every minute of every hour of every day of every week, etc etc. Users recieve mail constantly over time. They read it and then either delete it or store it in a subdirectory/folder. I imagine that my mail (located in a single subdirectory structure) is spread over the entire pool because it has been received over time. I believe the data is highly fragmented (from a file and directory perspective). The result of this is that backup thoughput of a single filesystem in this pool is about 8GB/hour. We use EMC networker for backups. This is a problem. There are no utilities available to evaluate this type of fragmentation. There are no utilities to fix it. ZFS, from the mail system perspective works great. Writes and random reads operate well. Backup is a problem and not just because of small files, but small files scatterred over the entire pool. Adding another pool and copying all/some data over to it would only a short term solution. I believe zfs needs a feature that operates in the background and defrags the pool to optimize sequential reads of the file and directory structure. Ed -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
