ZFS Shows Up in New Leopard Build 351
Udo Schmitz writes "As a follow-up to rumours from May this year, World of Apple has a screenshot showing Sun's Zettabyte File System in "the most recent Build of Mac OS X 10.5 Leopard". Though I still wonder: If it is not meant to replace HFS+, could there be any other reasons to support ZFS?"
Exciting! (Score:4, Interesting)
--jeffk++
Reasons to support? Servers (Score:5, Interesting)
For some reason... (Score:2, Interesting)
ZFS is overkill for a laptop - for now (Score:5, Interesting)
- They had implemented everything I thought they should, and
- That only accounted for about 40% of the features of ZFS.
Calling it the last word in filesystems might be hyperbole, but I expect ZFS to last a good 10-20 years, which is quite respectable for a filesystem, and I wouldn't be surprised if it lasted longer. Is it a replacement for HFS+? Not yet.HFS+ is a very nice filesystem for single user systems with a single disk. It implements journalling, has reasonable performance, and has good metadata support. For the average users at the moment, the only real advantage of ZFS would be snapshots, and these are not too difficult to implement for other filesystems.
ZFS, however, is much better when you have multiple physical disks. At the moment, only the top-end Macs have more than one disk. This is likely to change in two ways:
- Cheap flash,
- Network storage
For a home user, ZFS could handle backups trivially by plugging in a large flash drive and adding it to the pool. I suspect this will be one mechanism Time Machine will use. Due to the way ZFS works, you can just mirror a part of the directory tree (e.g.ZFS is not needed as a replacement for HFS+ in 2007, but it probably will be in 2008-9. ZFS is a 128-bit filesystem, which means it is designed to last for a long time. We will probably never need a 128-bit filesystem (unless we actually want to build hard drives the size of planets with single-atom sectors), but we will need a 65-bit filesystem once we get to around 10 Exabytes. This won't happen with single drives for a while, but it will with RAID arrays.
It's to support Time Machine (Score:5, Interesting)
So it's about the snapshot ability of ZFS, and that's exactly what will be needed for Time Machine [apple.com].
Re:copy-on-write (Score:5, Interesting)
Mmap simple maps pages of a disk file into memory. If the disk file changes its physical location then the mapping is updated. When you call mmap, you give it a disk file, an offset, and an extent. It is up to the VFS layer to translate this into physical mappings. LFS has the same issues, and these were solved well over a decade ago.
If you invoke mmap with MAP_PRIVATE, this actually makes it easier; if someone else updates the file then you just keep the existing mapping.
ZFS + Timemachine (Score:3, Interesting)
What? Of course it is (Score:3, Interesting)
The answer is that it probably is meant to replace HFS+, but since ZFS is not bootable yet (including for Solaris 10) Apple can take the time to introduce ZFS, build tools for easier management, and let people get familiar with the FS before they have to drop HFS+.
HFS' lifetime has already stretched far beyond what it should have, it's time for Apple to think of its next generation FS, and ZFS is an extremely promising FS with heaps of amazing features Apple has already started to integrate into its UIs with Leopard (Time Machine + ZFS Snapshots anyone?).
ZFS also shows strong promises as both a home and a server FS.
They already have UFS, and don't use it... (Score:3, Interesting)
In fact HFS+ is *so* bad that if it wasn't for a couple of apps that absolutely freak out if they don't have their pet un-emulated feature I would have gone to UFS long since... even if I lost Spotlight completely. Until my Mac I had never run into a file system that wasn't so badly damaged as to be unbootable that coudn't be repaired by fsck... but apparently with HFS+ just running it "too full" can trash it, and I lost my system disk on my old G4 three months running because of that!
So I wouldn't hold out any expectations of ZFS being implemented in any useful way. They already have better file systems than HFS+ and they're not using them.
Re:ZFS vs HFS vs NTFS? (Score:3, Interesting)
Mac OS X Server 10.4 (Tiger) already has this. See: http://www.apple.com/server/macosx/fileprint.html [apple.com]
There is a "File Services" white paper linked off of he above page but here is the relavant marketing:
Re:copy-on-write (Score:5, Interesting)
Makes use of copy-on-write; rather than overwriting old data with new data, it writes new data to a new location and then overwrites the pointer to the old data
It may do, but like many things there are alternative approaches.
From working on embedded hardware with flash memory, this makes me wonder whether possible addition of ZFS is meant to be for flash storage? Let me explain: flash memory has a fairly limited write-count, relative to hard disks, so to compensate for this memory is written in a circular fashion, to ensure that a given sector is written the least often possible. In addition to this, from what I can tell, Apple's main sales point are low profile computers and portables. The latter would benefit from flash storage as means of extending battery life, even if it is for a certain elements, such as for the OS which is accesed far more frequently than anything else on disk. Given this I wouldn't be surprised to see flash memory in future models of Apple portables, using ZFS, while HFS+ is still used for the hard disks.
This is pure speculation, but I feel that it has a high probabilty of being near the mark.
Re:going for Linux incompatibility, it seems (Score:1, Interesting)
Apple needs X11 to get people building scientific apps on Linux and Solaris. Its actually one of the best X implementations I've used (X.org, XFree86, Irix X Server)
...so how does one define "capacity" therein? (Score:4, Interesting)
for starters, does the FS "know" that i've just clicked "Save As" in my word processor? what about copy and pasting a file back into the same directory to make a local copy? Also? is it just within variations on the same file? if i have a particular setup exe on my system but forget, and download it again to the desktop surely the FS has no initial way of knowing that they are one and the same, does some funky heuristic happen?
basically: does the OS's read/write/copy/delete functionality have to invoke copy-on-write via a FS API or is it built in for every single sector-sized chunk that gets stuffed into the FS?
the next question is the one in my subject: how therefore do you define "capacity"? if i've got a bunch of files that take up 700mb on a ZFS device and try to back up to a (Joliet) CD will i get a message telling me that the CD doesnt have room? i can imagine this scenario being unlikely with optimised binary data (jpegs and mpegs) but if i'm backing up a dev environment with autobackups (main.c,main.c.bak.001,main.c.bak.002,etc.) and manually created and dated directory tree "snapshots" (dev,dev_backup_2006-12-18,dev_backup_2006-12-01,
Send/receive useful for .mac sorts of features (Score:4, Interesting)
ZFS lacks decent backup support (Score:1, Interesting)
Not sure about you but I really wouldn't like to try and restore data from the
Re:going for Linux incompatibility, it seems (Score:3, Interesting)
I agree that ext3 isn't the best thing out there for Linux, and I don't even use it myself. However, I would suggest that the reason for so many people still using ext3 is that most other filesystems aren't better enough to encourage people to move away from ext3. Look at some of the posts under this story - you will find stories of people moving from Linux to Solaris, really just because they want the features of ZFS. There is demand for ZFS in the Linux kernel, and if it becomes a common filesystem on OSX, I predict the demand will only increase. I don't expect ext4 will satisfy this demand, either.
Re:Reasons to support? Servers (Score:2, Interesting)
"Porting ZFS to Linux is complicated by incompatibilities between CDDL, the license its source is released under, and GPL, the license which governs the Linux kernel. To work around this problem the Google Summer of Code program is sponsoring a port of ZFS to Linux's FUSE system[10] so the filesystem will run in userspace instead. However, running a file system outside the kernel on Linux has significant perfomance impact." (from http://en.wikipedia.org/w/index.php?title=ZFS&old
Re:Secure Delete? (Score:1, Interesting)
Re:ZFS would be cool (Score:1, Interesting)
Re:Secure Delete? (Score:2, Interesting)
So in other words you can't reliably delete a file on many modern filesystems anyway (unless there are more advanced programs than shred?), and ZFS is no different. I think that melting your hard drive is the suggested solution.