Large sites that have centralized their data with a SAN typically have a storage device export block-oriented storage to a server, with a fibre-channel or Iscsi connection between the two. The server sees this as a single virtual disk. On the storage device, the blocks of data may be spread across many physical disks. The storage device looks after redundancy and management of the physical disks. It may even phone home when a disk fails and needs to be replaced. The storage device provides reliability and integrity for the blocks of data that it serves, and does this well.
On the server, a variety of filesystems can be created on this virtual disk. UFS is most common, but ZFS has a number of advantages over UFS. Two of these are dynamic space management and snapshots. There are also a number of objections to employing ZFS in this manner. ``ZFS cannot correct errors'', and ``you will lose all of your data'' are two of the alarming ones. Isn't ZFS supposed to ensure that data written to the disk are always correct? What's the real problem here? This is a split responsibility configuration where the storage device is responsible for integrity of the storage and ZFS is responsible for integrity of the filesystem. How can it be made to behave in a reliable manner? Can ZFS be better than UFS in this configuration? Is a different form of communication between the two components necessary in this case? -- -Gary Mills- -Unix Support- -U of M Academic Computing and Networking- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
