Recover Open Directory/LDAP on OS X

Occasionally, after a power failure or a forced system restart, you may have an issue with Open Directory starting again. Often it will appear to be “on” in the but under Servers is displayed “Unable to Load Replica”, even if yours is a Master.

Executing sudo /usr/libexec/slapd -Tt will often result in a string of errors including bi_db_open failed! (12)

A corruption of data in two possible locations causes this.

First try:

Execute sudo /usr/libexec/slapd -Tt and you should see:

56639871 bdb_monitor_db_open: monitoring disabled; configure monitor database to enable
config file testing succeeded

If you still get an error, proceed below.

Second try:

Execute sudo /usr/libexec/slapd -Tt and you should see:

56639871 bdb_monitor_db_open: monitoring disabled; configure monitor database to enable
config file testing succeeded

Once recovered, start things up again with:

Worst case, restore from backup:

I have seen a case where /var/db/openldap/authdata/id2entry.bdb is so damaged that a repair simply will not work. In this case restoring the file from a last known good backup is your only recourse. Once restored from a drive clone or other backup, re-run the above to be sure the configuration passes.

SMART Hard Drive Monitoring – Windows and Mac OS

Over the years I’ve seen a lot of hard disk failures. People are often incredulous that it could happen to them. As technology has progressed, just about all vendors include some sort of SMART diagnostics in their OS and/or motherboard EFI/BIOS.

SMART is an acronym for Self-Monitoring, Analysis, and Reporting Technology. Simply, all modern hard drives have the capability to report various parameters about themselves. Whenever a parameter goes out of bounds it can be an early warning sign of a failure and can help you avoid disaster.

Unfortunately, the included monitors are somewhat limited and often you have to go looking for your drive monitoring data since there are almost no proactive alerts.

I’m going to quickly go over two of my favorite utilities that actively alert you to pending drive issues: DriveDx for Mac OS and Acronis Drive Monitor for Windows. Since they closely resemble each other in features, I’ll put some screenshots side-by-side below that you can click for larger versions.

The most important thing about these utilities is that they both run in the background and monitor your drive(s) continually for issues and instantly alert you when there is a problem. DriveDx lives in the OS X Menubar and Acronis Drive Monitor is in the Windows Notification Area.








Both give a quick overview of the condition of your drive and alert of problems. But, what if you have a home server or a computer that runs tasks where you are not always near it? No problem, both offer the ability to send you email alerts on problems or even just a weekly status report on your drive!










One of the best features of each application is the ability to see every indicator and threshold of your drive(s) in a very detailed view along with the ability to do drive tests.









There are many options to explore in both programs and I can’t possibly cover every detail in a Tech Trinket. The one thing of note DriveDx currently offers that Acronis Drive Monitor does not is the ability to reference an on-line database of statistics about drive models and their failure history and will also use that information in its predictive analysis.

I should note that even with these utilities monitoring your drives, there is no substitute for backing up your data. Backing up your important files is the only sure way to avoid data loss in the event of a sudden drive failure.

DriveDx for Mac OS is $19.99 for a single license and $39.99 for a family pack that can be installed on up to 5 computers.

Acronis Drive Monitor for Windows is free for personal use.