Regular old fashioned ZFS has filesystems and snapshots. Recentversions of ZFS add a third object, called bookmarks . Bookmarksare described like this in the zfs manpage (for the ' zfs bookmark 'command):

Creates a bookmark of the given snapshot. Bookmarks mark the pointin time when the snapshot was created, and can be used as theincremental source for a zfs send command.

ZFS on Linux has an additional explanation here:

A bookmark is like a snapshot, a read-only copy of a file system or

I mentioned recently how a firmware update fixed a 3ware controllerso that it worked . As it happens, myexperiences with this machine nicely illustrates the idea thatsometimes it can be hard to tell one failure from another, or toput it another way, when you have a failure it can be hard to tellwhat the actual cause is. So let me tell the story of trying toinstall this machine.

Like many places within universities, we don't have a lot of money,but we do have

I mentioned recently that my Fedora25 version of choqok doesn't supportsome of the latest Twitter features, like quoted tweets (and thiscauses me to wind up with a bit of a Rube Goldberg environment todeal with it). In a comment, Georg Sauthoff suggested taking a look at Corebird ,which is a (or the) native Gtk+ Twitter client. I've now done so andI have some views as a result, both good and bad.

The good first. Corebird is the

A while ago I got some SSDs for my kind of old home machine but didn't put them to immediate use for variousreasons . Spurred on first by the feelingthat I should get around to it sometime, before my delay got tooembarrassing, and then by one of my system drives apparentlygoing into slow IO mode for a while,I've now switched my root filesystem over to my new SSDs. I've donethis process before, but this time around I want to write down notesfor

I tweeted :

. @erchiang 's pup tool justturned a gnarly HTML parsing hassle into a trivial shell oneliner. Recommended. https://github.com/ericchiang/pup

I like pup so much right now that I want to explain this and showyou what pup let me do easily.

I read Twitter through a moderately Rube Goldberg environment ( tothe extent that I read it at all these days ). Choqok , my Linux client, doesn't currentlysupport new Twitter features like long tweets

There are probably places that routinely apply firmware updates toevery piece of hardware they have. Oh, sure, with a delay and instages (rushing into new firmware is foolish), but it's always inthe schedule. We are not such a place. We have a long history oftrying to do as few firmware updates as possible, for the usualreason ; usually we don't even considerit unless we can identify a specific issue we're having that newfirmware (theoretically) fixes.

I recently read the Archive Team's Robots.txt is a suicide note ( via ), whichstrongly advocates removing your robots.txt . As it happens, Ihave a somewhat different view (including about how sites don'tcrash under load any more; we have students who beg to differ ).

The simple way to put it is that the things I add to robots.txt are hints to web spiders. Some of the time they are a hint thatcrawling the particular URL hierarchy will not be

At least on Unix systems, time is a subtle but big pain forprogrammers. The problem is that because the clock can jump forward,stand still (during leap seconds), or even go backwards, yourexpectations about what subtracting and adding times does can windup being wrong under uncommon or rare circumstances. For instance,you can write code that assumes that the difference between a timein the past and now() can be at most zero. This assumption recentlyled to a Cloudflare DNS outage during a leap

We recently inherited a 16-drive machine with a 3ware hardware RAIDcontroller and now I'm busy trying to put it to work. Our firstpreference is to ignore the RAID part and just the raw disks, whichmay or may not work sufficiently well (the omens are uncertain atthe moment). If we have to use the 3ware hardware RAID, we'll needthe proprietary tools that 3ware supplies. And that has turned outto be a problem .

Once upon a time,