The machine is a mid-2012 MacMini that operates as a server (colocated in a remote data center).
The MacMini has an external USB hard drive to provide backup storage (WD Elements Portable 2TB, USB powered)
Every night (at 2 am) the startup volume (internal SSD) is backed up to the external drive using the application Carbon Copy Cloner (with automated task).
From the task history I can see the backup always takes approximately 30 mins (there are dozens of entries in the history).
The last backup took 1h 45m.
Despite no error were reported by CCC, I am wondering:
- what may have caused that?
- is it a signal of imminent failure?
- what tools may I use to investigate the issue?
I know for sure that:
the volume of data copied/synced was approximately the same as previuos backups
the issue is with the external HDD not the internal SSD (because the HDD is subsequently backed up to a remote mac and also this operation did take much longer)
the HDD is not full (about 50% available)
there is almost no load/activity on the server during backup as it is performed at late night when no one use the server
I investigated CCC's log files but found nothing relevant.
I re-run manually the backup task and this time it took again the normal time (~30 mins)
Still I'm concerned that the single episode may be a signal of imminent failure.