On Fri, Dec 12, 2008 at 8:16 PM, Jeff Bonwick <jeff.bonw...@sun.com> wrote:
> > I'm going to pitch in here as devil's advocate and say this is hardly > > revolution. 99% of what zfs is attempting to do is something NetApp and > > WAFL have been doing for 15 years+. Regardless of the merits of their > > patents and prior art, etc., this is not something revolutionarily new. > It > > may be "revolution" in the sense that it's the first time it's come to > open > > source software and been given away, but it's hardly "revolutionary" in > file > > systems as a whole. > > "99% of what ZFS is attempting to do?" Hmm, OK -- let's make a list: > > end-to-end checksums > unlimited snapshots and clones > O(1) snapshot creation > O(delta) snapshot deletion > O(delta) incremental generation > transactionally safe RAID without NVRAM > variable blocksize > block-level compression > dynamic striping > intelligent prefetch with automatic length and stride detection > ditto blocks to increase metadata replication > delegated administration > scalability to many cores > scalability to huge datasets > hybrid storage pools (flash/disk mix) that optimize > price/performance > > How many of those does NetApp have? I believe the correct answer is 0%. > > Jeff Seriously? Do you know anything about the NetApp platform? I'm hoping this is a genuine question... Off the top of my head nearly all of them. Some of them have artificial limitations because they learned the hard way that if you give customers enough rope they'll hang themselves. For instance "unlimited snapshots". Do I even need to begin to tell you what a horrible, HORRIBLE idea that is? "Why can't I get my space back?" Oh, just do a snapshot list and figure out which one is still holding the data. What? Your console locks up for 8 hours when you try to list out the snapshots? Huh... that's weird. It's sort of like that whole "unlimited filesystems" thing. Just don't ever reboot your server, right? Or "you can have 40pb in one pool!!!". How do you back it up? Oh, just mirror it to another system? And when you hit a bug that toasts both of them you can just start restoring from tape for the next 8 years, right? Or if by some luck we get a zfsiron, you can walk the metadata for the next 5 years. NVRAM has been replaced by flash drives in a ZFS world to get any kind of performance... so you're trading one high priced storage for another. Your snapshot creation and deletion is identical. Your incremental generations is identical. End-to-end checksums? Yup. Let's see... they don't have block-level compression, they chose dedup instead which nets better results. "Hybrid storage pool" is achieved through PAM modules. Outside of that... I don't see ANYTHING in your list they didn't do first. --Tim
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