Intel Mac I/O Speed Monday, March 06, 2006

As you probably know from a previous post, we’re working on Universal versions of all of Shirt Pocket’s applications, including SuperDuper. (We’re in late-stage testing with SuperDuper, and it should be out reasonably soon.)

One thing we’ve been able to confirm: disk I/O on the Intel Macs is much faster than it is on the Power PC ones—seemingly about twice as fast.

In fact, SuperDuper builds about twice as fast on the MacBook as it does on a dual-2.5Ghz G5 desktop, and that’s primarily I/O related.


Horn tootin’ Monday, February 27, 2006

As backing up is even less exciting than doing your tax return and certainly easier to forget, an application named SuperDuper! takes care of the chore daily and automatically. It’s the first back-up application for the Mac that speaks to you in English rather than Geek and works perfectly. Ever the Doubting Thomas, I check the ‘bootability’ of the external drive monthly and compare the files sizes on the two 250 gB Lacies weekly to see that they remain identical.

via Thomas Pindelski’s Photographs, Photographers and Photography. Thanks, Thomas!

Unremovable files Monday, February 20, 2006

One of the interesting things that happens when you do a “live” backup—that is, back up the volume that you’re booted from—is copy files that are currently open.

Normally, this isn’t a huge problem. But, on occasion, things go horribly w0rng. This is a story of one of those things that happens every so often with SuperDuper, and what we’ve done about it. It’s a mite technical, but hopefully interesting.

As you probably know, under OS X files have an owner, a group, and a “mode”. These three things work together to determine who can read, write, execute and do other things to the files on your system.

Less well known are the “flags” that are associated with the files as well. For example, the “immutable” flag—uchg—can be set to prevent a file from being modified, regardless of its “mode”. There are a number of flags that can be associated with files and SuperDuper needs to properly replicate them when copying.

So far so good.

Every so often, though, we get reports of users who have files on their destination volumes that can’t be removed during Smart Update. The error always looks like this:

| 06:02:18 PM | Info | Warning: error clearing immutable flags: 77600100 for: /Volumes/G5/private/tmp/sort9qlI6c
| 06:02:18 PM | Info | Error removing item: /Volumes/G5/private/tmp/sort9qlI6c of type: 100000, Operation not permitted
| 06:02:18 PM | Error | SDCopy: Error deleting /Volumes/G5/private/tmp/sort9qlI6c
| 06:02:18 PM | Error | : Operation not permitted

We found that we needed to remove a file on the destination. But when we tried to clear its immutable flag, we couldn’t. The only solution was to use Erase, then copy which—while it worked—was inconvenient.

We were recently finally able to reproduce the issue in house, and what we found was quite curious.

When a file is being written at the same time we’re backing it up, it’s possible for that file to look “weird” in the file system. When the above happens, it seems that the directory entry isn’t completely updated, and—in this unusual state—some flags are set that result in the above behavior. Here’s the above file’s directory entry, listed with “ls -lo” (which lists flags too):

---s-wS--- 1 nobody 3221220928 sappnd,arch,schg 524237 Dec 31 1969 sort9qlI6c

So, weird stuff. The group is complete garbage, and the sappnd and schg flags are set. And—worse—since the system returned that junk to us, we faithfully replicated it on the copy.

Why worse, you might ask? Because while you can set the sappnd and schg flags, you cannot reset them while booted normally. And, schg is the “system immutable” flag: it prevents the file from being deleted. Once you have this flag set, that file’s going nowhere.

The reason for this is that FreeBSD—the Unix that OS X is built on top of—has a concept of “security levels”. By default, our Macs boot up and run in “Secure level 1”, which prevents anyone from writing in certain folders like /dev/mem and /dev/kmem, even with escalated privileges (such as “root” access). And, in secure level 1, schg and sappnd flags cannot be removed.

And how can you get to securelevel 0 or -1, where they can? You have to boot into single user mode.

(You can learn some more about the various BSD security levels at this page.)

Yikes! What that means is once you’ve set these flags, you’ve basically got to go super-geek to unset them.

It’s clear we can’t ask our users to reboot into single user mode to fix this kind of thing, so we decided that the best thing is to detect the “garbage” case as best we could, and—in that situation—mask out the schg and sappnd flags when copying. The data we’re given by the OS is still wrong, but at least the copy won’t suffer for it, and the user won’t have to erase their backup next time around.

This fix, as well as some other stuff I’ll be talking about over the next few days (including native Intel support), will be coming in v2.1 of SuperDuper—keep an eye out for it!

The Simple Life Friday, February 10, 2006

"norrebo” blogs about his experiences backing up his PowerBook to an HFS+ volume that he also accesses from his Windows machines using Mediafour’s MacDrive:

The total cost for this adventure was $265.94 ($188 for the disk, $27.95, for SuperDuper!, and $49.99 for MacDrive). But knowing that I’ve got a bootable image of my Powerbook disk? Priceless.

via The Simple Life. Glad you like it, “norrebo”, and thanks for sharing the technique you use!
Getting Right Back to Work Thursday, February 02, 2006

Khoi Vinh, late of Behavior (now the Design Director for the New York Times) and the genius of grid-based designs (I wish my own site looked one-one-millionth as good as stuff he tosses into the trash), recently had a catastrophic hard drive failure (all too common, believe me):

I feel very fortunate, though; immediately after the first signs of trouble, I quit my procrastination and scheduled full backups of the hard drive on alternating nights to two different external FireWire drives — aided in no small part by the sheer awesomeness of Shirt Pocket Software’s invaluable SuperDuper! product. As a result, I lossed less than a day’s worth of work; not perfect, but it could have been loads worse.

SuperDuper! made it exceedingly easy for me to create a complete, bootable mirror of my hard drive, which actually allows me to continue to use the same system — with all of my files, preferences and software tweaks intact — with another Macintosh. I pulled my old Aluminum 15-inch PowerBook G4 out of retirement and booted it from one of the backup FireWire drives.

via Subtraction, Khoi’s blog. Exactly the idea—glad SuperDuper! could be of service!

Going Universal Wednesday, February 01, 2006

Our “production” iMac hit the Shirt Pocket loading dock (aka my front step) yesterday, and I’ve been busily working on updates to netTunes and launchTunes while Bruce works on completing the next update to SuperDuper!, which looks like it will be Universal as well.†

It’s been nice to get back to Xcode after some time off (my design/marketing/documentation/support/etc duties keep me away from it more than I’d like), and it didn’t take more than a few hours to do the netTunes conversion—it’s up and running as I type, and works great.

The big challenge with netTunes was the screen “scraping”—the code has some byte-order dependencies because of pixels, and I wasn’t looking forward to re-writing the “inner loop” to handle all the various cases with Thousands and Millions of colors using both MMX and Altivec. Blegh.

Fortunately, there was an elegant solution. Since the Intel Mac is Tiger-only, I was able to make use of some the new Accelerate framework APIs to eliminate byte order dependencies and—at least under Tiger—about two pages of nasty code. Since the Intel Macs can’t run Panther, I didn’t have to change the already-working parts. The result? Both the Intel and PPC versions benefit, at least under 10.4.

It’s always a good feeling when you can delete code and leave the hardware-specific optimization up to the guys who live and breathe vector processing units, let me tell you.

Anyway, we’re working hard to get the Universal binaries out the door. Obviously, it’s important to do extensive testing using real, production hardware—and we’re doing just that.

† - Updated for the exclamation point haters. You know who you are.

Slobber, slobber Tuesday, January 31, 2006

You can boot off USB drives on Intel-based Macs. This opens the world of USB 2.0-only drives to Macs users as bootable backup devices. That sound? It’s David Nanian drooling.

from Tales from the Red Shed & Jonathan Rentzsch

Egad, was I that loud? >wipes chin<

UK Macworld Chimes In! Friday, January 20, 2006

Although I haven’t yet seen the full review, some UK Macworld readers have written in to tell me that there’s a full page review of SuperDuper in the latest issue. 4.5 stars, and this great quote:

There are just three groups of people who should be using this excellent utility. Lunatic frontiersmen with a penchant for early beta software, paranoid data hoarders who think that the next crash is just a restart away, and everybody else.

from Richard Dyce’s review in Macworld UK‘s February 2006 issue. Thanks, Richard & Macworld UK!

MacFixIt Toolbox Awards, Awarded! Wednesday, January 04, 2006

Hey, cool! It looks like SuperDuper! received a Gold MaxFixIt Toolbox Award this year!

A good backup strategy should be the base of any troubleshooting plan. This versatile disk copying program can make a straight copy, or “clone”—useful when you want to move all your data from one machine to another, or do a simple backup. The real power, however, lies in its ability “checkpoint” your system, preserving your computer’s critical applications and files while you run on a working, bootable copy.

Thanks, MacFixIt!
Eddy! Wednesday, December 14, 2005

Let me be the second to announce that SuperDuper! 1.5—the old version—has won a 2005 Macworld Eddy!

Bruce and I are incredibly happy that the editors at Macworld found us worthy of this honor: thanks to all, and to all the customers out there who continue to support us by registering. Hard to believe that both of Shirt Pocket’s main products have won Eddy awards… wow. It’s greatly appreciated.

(By the way, there’s a brief interview with me on today’s Macworld podcast, too, should you not be tired of my babbling...)

And with that, back to work making things even better!

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