In theory inPython, tuples are for heterogeneous data and lists are for homogeneousdata. Except, well, tuples and lists have 'side effects': tuplesare read-only and lists are not. Which means that if you take therestriction on lists seriously, you do not have a core data type forordered writeable heterogeneous data (and maybe also one for read-onlyhomogeneous data).

(While this is a theory that's probably more honored in the breach thanin practice, I think that

The somewhat new collections module has a number of usefulthings that obsolete several of the things I've done by hand in thepast. For my own reference if nothing else, here's more or less whatits solutions obsolete and when each solution was introduced.

• defaultdict obsoletes my use of dict.setdefault() . It was introduced in Python 2.5.

• namedtuple obsoletes some but not all of my various forms of structures in Python. It wasintroduced in Python 2.6.

The reason namedtuple doesn

Suppose that you have some ZFS-based NFS fileservers , perhaps in some sort of failover configuration,and that you want to export some pools from one. So you do:

# zpool export tankcannot unmount '/x/y': Device busy

The usual set of tools don't show any local processes using thefilesystem (not that there really are any, the server being purely anNFS server), and there's no actual NFS activity. In short: ratherpuzzling. Also annoying, since

Since I had a Mini 12 around and I'd previously done similar measurements with an Asus Eee PC, hereare some measurements about what seems to draw power on a Dell Mini 12.The necessary disclaimers are that all of these measurements are madewith a power meter while the Mini 12 was on wall power, running Dell'sversion of Ubuntu.

(Ubuntu exposes a lot more controls for this than Asus's Eee setup, soI suspect you could duplicate these results on battery power or

I have an ASUS Eee PC (one of the original small ones) and I've recentlybeen playing around with a loaner Dell Mini 12. Since it has to go back,now seems like a good time to do a short comparative review.

From my perspective, the Mini 12 has only three real advantagesover the Eee PC: it has a significantly larger screen, it suspendsto disk because it has a hard drive instead of a small SSD, and itruns a more or less standard Ubuntu

One of the alternatives to package downgrades for problems like myconcerns with trying Fedora Rawhide is whatI'll call 'rollbacks': whole system snapshots that you can easilyrevert to. However, I'm far less enthused about rollbacks than I amabout downgrades, and I don't think they're as good a solution for thisproblem.

The problem with rollbacks is that they are too comprehensive. In reallife, you don't always detect problems right away, which means that youcan wind

Apart from the outright issue with the ZFS failmode setting, here issome things that I've run across during our testing and usage of ZFS onSolaris 10 update 6:

• ' zpool status -x ' is of the opinion that a pool using an olderon-disk format is an error, or at least something that should showup in its output. It is completely mistaken and this mistake makesit far less useful than it could be, since it now reports all ofour pools all of the time

One of the things I wish for every so often is the ability to downgrade Linuxdistributions, not just upgrade them (which is common and generally wellsupported; I can think of only one large Linux distribution withoutupgrade support, and you can argue that Red Hat Enterprise Linux isa special case). This wouldn't be as good as various forms of 'liveupgrade', but it would still be useful and it would certainly makeme a lot less nervous about doing upgrades.

Conceptually, a downgrade is

Sparked by Pete Zaitcev ,here's a thought: why don't I use Fedora Rawhide? That's a seriousquestion, since I'm sort of in the natural target audience; I've gotthe skills and the general interest and willingness, and I run and haverun relatively bleeding edge versions of various things (at one pointincluding kernels, although I've gotten lazy since then).

In thinking about it, what it comes down is that while I can standirritations, I