APFS purgeable space
  • I have a problem with purgeable space on an external SSD RAID volume formatted as APFS. This is related to the "Delete old files by free space" configuration option in SecuritySpy. It appears that the purgeable space is not taken into account, and so SecuritySpy ends up pretty much deleting every file. Not only that, but SecuritySpy then complains that the disk is not fast enough, which is certainly not the case for this SSD RAID volume. Currently "About This Mac --> Storage" shows 15.98TB free on the volume. From Terminal, "du -sh ." on the volume shows only 22G in use. SecuritySpy is the only software writing and erasing files on the volume. Disk Utility shows 15.53TB purgeable, which presumable are the files that SecuritySpy has already deleted (and perhaps are still available somehow in APFS snapshots). Is there any solution besides reformatting to a different filesystem type?

    This had been working find previously, but after upgrading to 10.15.5 this problem started occurring.
  • I would expect this problem if an old version of SecuritySpy (which doesn't know about purgeable space) were run on newer macOS systems with disks with this feature, however newer versions of SecuritySpy do take into account purgeable space. Basically, SecuritySpy adds up real free space plus purgeable space, and uses this number as the amount of free space on the volume. According to Apple this is the correct thing to do (as purgeable space is automatically purged by macOS when needed, so can effectively be treated as free space).

    So the first thing to do is to make sure you are using the latest version of SecuritySpy.

    If you are still having this problem with the latest version of SecuritySpy, please email us at support@bensoftware.com and include SecuritySpy's debug file (SecuritySpy menu -> Debug submenu -> Create Debug File On Desktop).
  • I'm on 5.2.2 and it says there is no update available. Again, this seemed to be working fine with Mac OS 10.15.4, so I suspect something went awry in the update. I went ahead and reformatted the RAID volume (still APFS) and will monitor the situation. Takes about 12 days or so before it will have a need to start deleting old capture files (after which I can access old capture files from a different non-SSD RAID system used with TimeMachine).
  • OK, let's see how things go after the reformat. If you end up having the same problem, please email us and we'll work with you directly to get to the bottom of the issue. When emailing, please supply as much info as possible include the debug file mentioned above, but also anything else you think would be useful (e.g. a screenshot of the Finder's "Get Info" window for the drive and the output of the "du" command you referred to above).

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