indicator 173 and the total data written are not given in any of the standard utilities bundled with Macs, nor as far as I can see in any of Apple’s bundled diagnostics, even those run from the command line. I gave example calculations in my previous article. Alternatively, you can get a rough estimate by assuming that wear is reasonably levelled across the storage blocks, and using the total amount of data written to the SSD and its capacity to calculate how much of the likely ‘wear’ has been used up. indicator number 173, Wear_Leveling_Count, which is a direct measurement of this. There are two useful measures of the expected lifespan of an SSD: all SSDs should monitor S.M.A.R.T. tools such as DriveDx can do so, but Disk Utility and other common tools will only warn you when the drive fails a test. If your Mac has an SSD, it is not easy to discover how worn out that is. That is an awful lot of Macs with SSDs, so even a small proportion of them with similar problems could mean that many users are facing expensive repairs. iMacs have been offered with Fusion Drives from late 2012 onwards. Apple has been fitting pure SSDs in MacBook Airs since January 2008, and in MacBook Pro models since late 2008. His iMac could be unique in this, but I suspect that there are others, perhaps many. Most likely, though, is that the wear levelling software has not always been working properly. monitoring on it is giving absurdly incorrect figures. Maybe his iMac has been running Apple’s iCloud services for Europe, or the S.M.A.R.T. There are several possible explanations for this. I have come across one user, with an iMac which has an Apple Fusion Drive with only three months of continuous use on the clock, whose SSD is now almost worn out. What we don’t know is how effective that is in each case. In practice, though, this is very dependent on software (or firmware) evening out the number of writes across the SSD – so-called wear levelling. Some predictions for the typical life of an SSD in a computer are very optimistic, perhaps more than ten years. The more that you use your SSD, the earlier it will fail. However, SSDs can only write data a certain number of times, and in any case cease functioning after around 10 years. Unlike hard drives, they cannot suffer mechanical failure, or problems with the magnetic material on a hard drive’s platters. I will probably just wait until I move the SSD into the Mini.A few days ago, I drew attention to potential problems in Macs with solid-state drives (SSDs) as they grow older, and the drives wear out. Now when I boot into Mojave, I can launch DriveDX but only the spinner shows up, so it seems the SSD is considered "external" even though it's the boot drive. Well, it's been a few months now and I still haven't found the time to do the switch - mostly because other items mone up in the priority list and running Mojave as the boot drive on an external USB 3.0 enclosure works just fine.ĭriveDX was migrated from ElCapitan on the spinner to Mojave on the SSD along with everything else via a clean Mojave install and Migration Assistant. Plan was to run like that for a ouple of weeks and if no issues install the SSD in the Mini to replace the spinner. Pressed for time and a bit cautious with my main Mac, I decided to run Mojave on the SSD in an external USB 3.0 enclosure and keep the internal ElCapitan spinner as a back up to fall back on if I didn't like Mojave. Then I decided to upgrade to Mojave, but I could use more internal storage and I also wanted to switch to an SSD for better performance with APFS so I bought a 1 TB Crucial SSD. DriveDX was originally installed on the 500GB internal spinner running ElCapitan.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |