We grow up, being taught that right is right, and wrong is wrong. That there is only the correct answer, and the wrong answer, and nothing in between.
So, is it a suprise that our testing tools are design to indicate that something is “healthly” or “failing”? Or “Good” or “Bad”?
History
S.M.A.R.T. (Self-Monitor, Analysis, and Reporting Technology) testing for hard drives was first introduced by IBM in 1992 with their IBM 9337 Disk Arrays for main frame servers. This version measured several key device parameters and evaluated them. The results would either indicate “Device is Ok” or “drive likely to fail soon”.
Compaq with Seagate, Quantum and Conner devised IntelliSafe, which was effectively a variant of PFA (“Predictive Failure Analysis”), IBM’s first version of SMART. The major difference is that the IntelliSafe system would communicate the data back to the operating system, which would then evaluate the drive’s status, instead of PFA which was based in the drives firmware.
The IntelliSafe version was submitted for standardization in 1995, and was supported by IBM, Seagate, Quantum, Conner and Western Digital. The revised standard was then named SMART.
The Assumptions that lead to Problems
A SMART test, does not guarantee a working drive. All that it does is help detect a failing or failed hard drive. In many cases a SMART test will help reveal or make it easier to troubleshoot a failing drive, but it only acts as a potential early warning detector.
Why? A SMART test only provides two values: “threshold not exceeded” and “threshold exceeded”. Often these are represented as “drive OK” or “drive fail” respectively. A “threshold exceeded” is intended to indicate that there is a relatively high probability that the drive will not be able to honor its specification in the future: that is, the drive is “about to fail”. The predicted failure may be catastrophic or may be something as subtle as the inability to write to certain sectors, or perhaps slower performance than the manufacturer’s declared minimum.
The status also does not necessarily gauge the drive’s past or present usability. If the drive has already failed, then the SMART status maybe inaccessible. In addition, if a drive has experienced issues in the past, but at that moment is not, then the SMART test may indicate that the Drive is sound.
The SMART standard also only refers to the signaling method between the drive, and the drive controller. So, a drive that supports SMART testing, may or may not include a temperature sensor. The specific sensors that should be tested are not specified in the SMART standard. Most external enclosures do not report SMART results over USB, or Firewire.
So why do I mention this? My Wife’s system was working fine while in Mac OS X 10.6, but when bootcamped over to Windows XP, she was complaining about “stuttering” or momentary freezes. After investigating, I discovered that the Hard drive was reporting write failures, and read issues with the pagefile. In otherwords, the hard drive that had just been installed 4 months ago, was bad.
The SMART tests did not reveal this on the Macintosh side, since it was a different partition that wasn’t being used on the Mac Side. Windows XP, just doesn’t have a built-in SMART test. So the OS was silently reporting this, and not reporting this critical issue to the User.
I find it slightly Funny though, Windows will display pop up messages from the System Tray for sometimes the silliest things, but can’t give me a popup indicating that there was a failure to write to the pagefile or to a drive.
The good news was that we were able to detect this before it became critical, and we had recent backups (Yeah! Time Machine!).
Someone stole John Boldt’s laptop out of the trunk of his car. Nothing really newsworthy about that. But according to a CTV Calgary article, that laptop contained the University of Calgary grad student’s nearly-completed master’s thesis, as well as his research and notes.
“It’s so many years of my life just thrown away,” Boldt told CTV. “The computer can be replaced. It’s what’s on it that can’t.” Unless an honest thief returns the precious files, Boldt figures that he can’t return to the University. His academic life and future career, judging from the article, are pretty much over.
I guess he wasn’t on a Mac, and using Time Machine. Or a internet based backup service… Or a thumb drive.
Come on folks, not backing up your critical data is just foolish…
Earlier this week Apple released to developers the fifth build of Mac OS X 10.6.5. The release comes just a couple of weeks after the previous release of Mac OS X 10.6.5.
The current version of Mac OS X Snow Leopard was released in mid-June after just under two months of developer testing.
Mac OS X 10.6.5 build 10H542 weighs in at 571MB for the delta update and contains six focus areas and no known issues. World of Apple sources state that Apple has not included a list of fixes with the latest build, yetMac Rumors has published a list.
Changes in build, according to Mac Rumors
- improve reliability with Microsoft Exchange servers
- resolve a delay between print jobs
- address a printing issue for some HP printers connected to an Airport Extreme
- resolve an issue when dragging contacts from Address Book to iCal
- address an issue where dragging an item from a stack causes the Dock to not automatically hide
- add SSL support for uploading files to iDisk
- resolve an issue with Wikipedia information not displaying correctly in Dictionary
- improve performance of MainStage on certain Mac systems
- resolve spacing issues with OpenType fonts
- improve reliability with some Bluetooth braille displays
- resolve a VoiceOver issue when browsing some web sites with Safari 5
- address stability and performance of graphics applications and game
Known Issues
- None
Focus Areas
- 3D Graphics
- iCal
- QuickTime
- Time Machine
- USB Devices
Well, Mac OS X has turned 10… Let’s take a look back at my list of best features that Mac OS X has introduced…
- Time Machine – Quite simply, this has brought backups to virtually everyone that wants it. While Retrospect, and other applications have their followers, Apple introduced a simple system that just by connecting another drive, your backup concerns are virtually eliminated. While not perfect, it is a major step forward and raises the bar on the commercial backup market.
- Native PDF support – All versions of Mac OS X have offered native PDF creation, reading, editing, and modification support. From any print dialog you can create a PDF file, really. Most people don’t understand that Acrobat Pro is only really needed for modifying forms, and other niche PDF features.
- Spotlight – It’s like having Google Desktop (TM) on your computer, searching your own system, and the other networked macs in your home lan.
- Boot Camp – The ability to run any Windows application or game you want, as long as you bring your own copy of Windows.
- Unix Support – The ability to use virtually any Unix based application, as well as the built-in File Sharing (Simba), and Web server (Apache), give us control and features that were undreamed of in the Mac OS 9 days.
- Quick Look – The ability to hit a key or a mouse button, and have the document opened immediately in the Quick Look browser…
Items to look forward to:
- OpenCL & Grand Central – Simplify multiple threaded applications, and simplify the use of multiple CPU cores, which have the potential to help optimize the performance of every CPU core you have in your system….
Time Machine is very boolean in it’s operation. It either was successful or failed. So if there is a single file that it can’t backup, it aborts it’s current backup, and shuts down until the next backup cycle. This isn’t exactly an optimal solution. Other Backup software (eg Retrospect) will log an error on a particular file, but continue with the current backup cycle, until done.
Time Machine does not have any built-in mechanism to verify a set of backups as being valid. That’s one issue with Time Machine, being consumer orientated instead of enterprise…
Sure, you could perform a Disk Repair in Disk Utility, but that doesn’t validate the Time Machine backup data. That instead will verify the structure and integrity of the backup disk. (Of course, Disk Warrior verifies / repairs in a complementary manner).
The only way that I see that you could verify the data in the backup is to do a full restore.
Well, I have just learned that Time Machine claims to have a verification method, if you are using a Time Capsule. Option-Click on the Time Machine Menu Extra, and you will see (starting with 10.64) a option called Verify Backups. This Apple Technote(HT4076) discusses the process, and it is simply running a Disk Utility / Verify Disk on the Time Capsule disk image. This does not necessarily verify the data was accurately backed up, but verifies the integrity of the Disk Image.
So, it doesn’t really verify your backup data… It’s verifying the backup file’s integrity…
So at this point, I still have not found a reliable method to verify Time Machine Backups….
So far, so good… I had an issue with a Western Digital External Firewire 400 Mybook 500Gb drive… After a few days, it would seemingly “go to sleep” and not always wake up properly for a Time Machine Backup…
Time Machine would start processing, but continue on indefinitely, and would get “stuck” in the backup… Cancelling would not stop it, I would have to manually remove the drive from the FW chain, causing the system to abort the backup….
That drive has now been moved to the END of the Firewire chain, and so far this issue has not yet re-appeared…. And it’s been roughly a week….
So, if you have Firewire issues, try moving devices around in the chain…
Since the release of Time Machine, backing your Mac up has never been easier. If you want to back up different sets of files to more than one drive, though, this script will help you do so.
Time Machine, in typical Apple fashion, will seamlessly back up your data with little effort on your part. However, when it comes to doing something a little more advanced, Time Machine isn’t quite wired to do so. It can back up to multiple disks, for instance, but you’d have to change the preferences every time, which can be a pain. Thus, if you want to, say, back up your whole disk to one drive and only one subset of files onto other drive, you’ll need to automate it yourself.
To start, open up Time Machine and configure it to back up to your first drive with your desired preferences. After it goes through the first backup, head into /Library/Preferences and rename the com.apple.TimeMachine.plist file to com.apple.TimeMachine.Disk1.plist (or whatever other name you want to call it instead of ‘Disk1′). Go back into Time Machine, plug in your second drive, set the preferences for it, and let it back up too. If you go back to /Library/Preferences, the com.app.TimeMachine.plist will have reappeared, and you can rename it to com.apple.TimeMachine.Disk2.plist.
Next, open up Applescript Editor and paste this template into the box:
property pth : “Macintosh HD:Library:Preferences:”
property d1name : “Backup Disk 1″
property d1 : “com.apple.TimeMachine.Disk1.plist”
property d2name : “Backup Disk 2″
property d2 : “com.apple.TimeMachine.Disk2.plist”
property active : “com.apple.TimeMachine.plist”
do shell script “defaults write com.apple.TimeMachine AutoBackup -bool false”
if (list disks) contains d1name then
tell application “Finder” to if exists (pth & d1) then
set name of file (pth & active) to d2
set name of file (pth & d1) to active
end if
else if (list disks) contains d2name then
tell application “Finder” to if exists (pth & d2) then
set name of file (pth & active) to d1
set name of file (pth & d2) to active
end if
end if
do shell script “defaults write com.apple.TimeMachine AutoBackup -bool true”
Time Machine can still only back up to one disk at a time, so the best way to do it is plug in the disk you want to back up and run the script. It will then automatically back up to that disk for as long as it’s plugged in. When you want to back up your second disk, just eject the first one, plug in the second one, and run the script again. Time Machine will then back up to the second disk with those preferences until you disconnect it. It’s not as perfect as being able to back up to both without fiddling with them, but it’s still a heck of a lot easier than manually moving preference files around yourself (or resetting the preferences every time you want to back up a new disk).