Good questions – wish I knew the answers. IIRC ZFS has the usual raft of options, so new disks can either be automagically added to the pool or the sysadmin can be queried. So I think it can be handled, and certainly would be for a consumer computer.

REM,

Apple folks were vociferous in maintaining that Time Machine did not rely upon ZFS, and I take them at their word. Having said that though, there is no doubt that Time Machine and other graphically oriented storage utilities become much simpler under ZFS. Also, I recently realized that ZFS has some important features for small, flash-based devices.

Robin

How comes? All you can be sure in that case is that you can detect an error when comparing read data and correspoding checksum. But still I don’t get how this prevents rodden bits for instance. It only helps detecting it! (same is true for md5sum).

Couple of points: Checksums don’t just say there is an error, they also correct most of them. If a block is really hosed, you rebuild from the RAID copy.

No RAID controllers means No RAID controllers. You may want to have dual interconnects to your storage with failover for redundancy, but all you need is something to send the bits over the wire – no XOR, no RAID 5, no cache. So failure modes should be much simpler and less frequent, which the checksums will catch.

Workloads:
ZFS is designed for heavy-duty server workloads just like Solaris runs all the time. It has fancy I/O scheduling algorithms that do smart things, plus its code is compact. Check out http://blogs.sun.com/roller/page/bill?entry=zfs_vs_the_benchmark for more info on performance.

I am spending countless evenings studing storage architectures and designs and it turns out the answer might be a osx upgrade away from being under my nose.

Your three posts give a great feature overview of ZFS and I love the simplicity of JBOD + ZFS = piece of mind for cheap.

But can you comment on what kinds of workloads this is planned for. When I see things like we don’t write over new data, I wonder if that’s a design that makes sense for heavy database workloads. Could you advise if this appeals to Apple Geniouses who are tired of crying power book users, or search engine wanna-be’s.

What about about us Enterprise LAMP on a shoe-string folks? In particular the heavy MySQL workload folks and Apache server folks.

P.S. the first link points to a word press login not the page you intended.

How comes? All you can be sure in that case is that you can detect an error when comparing read data and correspoding checksum. But still I don’t get how this prevents rodden bits for instance. It only helps detecting it! (same is true for md5sum).

> No RAID Cards or Controllers

If you are going for a serious RAID, you still should have more than one controller in order to ensure that a slightly failing controller doesn’t get you. Think for instance in the tape world where people write tapes with a unadjusted head and are not able to read the data on another drive. Same to a certain degree can be true for disks – you simply can’t trust the hardware underneath you, so you should have multiple channels and mirror ofter them (at least accross two of them).