Reinstalling Os X Yosemite


Since the latest Mac OS X update, 10.10 'Yosemite', was released last Thursday, there have been complaints springing up online of the progress bar woefully underestimating the actual time to complete installation. More specifically, it appeared as if, for a certain group of people (myself included), the installer would stall out at 'two minutes remaining' or 'less than a minute remaining'–sometimes for hours.

Mac OS users who want to install OS X 10.10 Yosemite on their machines and are facing issues installing the operating system for the first time on their Macs can follow a simple step-by-step guide. OS X Yosemite is free of charge, so no sale. Furthermore, OS X Utilities does not offer me an option, i.e. Any other version than Yosemite to reinstall - so even if I wanted, I wouldn't know how to choose Snow Leopard or the last version it ran on, Mavericks. May 08, 2015 Solution 1: Reinstall OS X. While not a technical solution per se, it is an effective one. Reinstalling OS X - even over an existing 10.10 install - will trigger the installer to recreate the. OS X re-install without loosing any information or apps, Yosemite OS X, mavericks osx.Macbook pro, iMac, Mac mini, Mac pro, Macbook retina display, macbook a.

In the vast majority of these cases, though, the installation process didn't hang, it was just performing a bunch of unexpected tasks that it couldn't predict.

During the install, striking 'Command' + 'L' would bring up the install logs. In my case, the logs indicated that the installer was busy right until the very last minute.

Not knowing very much about OS X's installation process and wanting to learn more, and wanting to answer why the installation was taking longer than the progress bar expected, I saved the log to a file on my disk with the intention of analyzing it before the installer automatically restarted my computer.

The log file from the Yosemite installer wasn't in a format that R (or any program) could handle natively so before we can use it, we have to clean/munge it. To do this, we'll write a program in the queen of all text-processing languages: perl.

This script will read the log file, line-by-line from standard input (for easy shell piping), and spit out nicely formatted tab-delimited lines.

We can output the cleaned log file with this shell command:

This cleaned log contains 6 fields: 'Month', 'Day', 'Time', 'Machine (host)', 'Service', and 'Message'. The installation didn't span days (it didn't even span an hour) so technically I didn't need the 'Month' and 'Day' fields, but I left them in for completeness' sake.


Let's set some options and load the libraries we are going to use:

Now we read the log file that I cleaned and add a few columns with correctly parsed timestamps using lubridate’s 'parse_date_time()' function

And remove the rows of dates that didn't parse correctly

The first question I had was how long the installation process took

Ok, about a half-hour.

Let's make a column for cumulative time by subtracting each row's time by the start time

In order to see what processes were taking the longest, we have to make a column for elapsed time. To do this, we can subtract each row's time from the time of the subsequent row.

Which services were responsible for the most writes to the log and what services took the longest? We can find out with the following elegant dplyr construct. While we're at it, we should add columns for percentange of the whole for easy plotting.

Reinstalling Os X YosemiteDownload

Ok, the 'OSInstaller' is responsible for the vast majority of the writes to the log and to the total time of the installation. 'opendirectoryd' was the next most verbose process, but its processes were relatively quick compared to the 'Unknown' process' as evidenced by 'Unknown' taking almost 4 times longer, in aggregate, in spite of having only 7% of 'opendirectoryd's log entries.

We can more intuitively view the number-of-entries/time-taken mismatch thusly:

As you can see, the 'Unknown' process took a disproportionately long time for its relatively few log entries; the opposite behavior is observed with 'opendirectoryd'. The other processes contribute very little to both the number of log entries and the total time in the installation process.

What were the 5 most lengthy processes?

The top processes were:

  • Unpacking and moving the contents of 'Essentials.pkg' into what is to become the newsystem directory structure. This ostensibly contains items like all the updated applications (Safari, Mail, etc..). (almost three minutes)
  • Archiving the old system logs (two and a half minutes)
  • Loading the kernel module that allows the onboard serial ATA controller to work (a little over a minute)

Let's view a density plot of the number of writes to the log file during installation.

This graph is very illuminating; the vast majority of log file writes were the result of very quick processes that took place in the last 15 minutes of the install, which is when the progress bar read that only two minutes were remaining.

In particular, there were a very large number of log file writes between 11:47 and 11:48; what was going on here?

Ah, so these processes are the result of the installer having to move files back into the new installation directory structure. In particular, the vast majority of these move operations are moving files related to a program called 'texlive'. I'll explain why this is to blame for the inaccurate projected time to completion in the next section.

Reinstalling Os X Yosemite

But lastly, let's view a faceted density plot of the number of log files writes by process. This might give us a sense of what steps go on as the installation progresses by showing us with processes are most active.

This shows that no one process runs consistently throughout the entire installation process, but rather that the process run in spurts.


the answer
The vast majority of Mac users don't place strange files in certain special system-critical locations like '/usr/local/' and '/Library/'. Among those who do, though, these directories are littered with hundreds and hundreds of custom files that the installer doesn't and can't have prior knowledge of.

In my case, and probably many others, the estimated time-to-completion was inaccurate because the installer couldn't anticipate needing to copy back so many files to certain special directories after unpacking the contents of the new OS. Additionally, for each of these copied files, the installer had to make sure the subdirectories had the exact same meta-data (permissions, owner, reference count, creation date, etc…) as before the installation began. This entire process added many minutes to the procedure at a point when the installer thought it was pretty much done.

What were some of the files that the installer needed to copy back? The answer will be different for each system but, as mentioned above, anything placed '/usr/local' and '/Library' directories that wasn't Apple-supplied needed to be moved and moved back.

/usr/local/ is used chiefly for user-installed software that isn't part of the OS distribution. In my case, my /usr/local contained a custom compliled Vim; ClamXAV, a lightweight virus scanner that I use only for the benefit of my Windows-using friends; and texlive, software for the TeX typesetting system. texlive was, by far, the biggest time-sink since it had over 123,491 files.

Reinstalling Os X Yosemite

In addition to these programs, many users might find that the Homebrew package manager is to blame for their long installation process, since this software also uses the /usr/local prefix (although it probably should not).

Among other things, this directory holds (subdirectories that hold) modules and packages that the Apple-supplied Python, Ruby, and Perl uses. If you use these Apple-supplied versions of these languages and you install your own packages/modules using super-user privileges, the new packages will go into this directory and it will appear foreign to the Yosemite installer.

To get around this issue, either install packages/modules in a local (non-system) library, or use alternate versions of these programming languages that you either download and install yourself, or use MacPorts to install.


You can find all the code and logs that I used for this analysis in this git repository

Reinstalling Os X Yosemite A Required Download Is Missing

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Hi all

I am trying to reinstall OS X Yosemite onto a MacBook Pro Late 2008 version. We are selling the Mac, and have conducted the steps described in 'What to do before selling or giving away your Mac', i.e. deauthorizing from iTunes etc, and erasing all data from the harddrive. I am using an ethernet connection.

When trying to install Yosemite, after entering my Apple ID and password, I keep getting the message 'This item is temporarily unavailable'.

Reinstall Os X Yosemite Disk Locked

Reinstalling Os X Yosemite 10 10

I found members stating that this can be due to the App Store being flooded with requests, but this has been going on for three days now, and I find that a bit unusal.. Especially since the first installation onto our old Mac took one evening..

Os X Mountain Lion

Thank you all for any help and advice you can provide!


MacBook Pro, OS X Yosemite (10.10), MacBook Pro Late 2008

Reinstalling Os X Yosemite Installer

Posted on Nov 7, 2014 10:58 AM