Check speed

Checking backups is best done in between making them. But what if a backup is taking hours, and never seems to complete? You can then, or at any other time, check Time Machine’s recorded transfer rates during a backup. In Catalina, these are given in detail in the log, and T2M2 can display them. Previous versions of macOS have similar records, but may not show the same or any detail. These are most useful when Time Machine is making its first full backup.

Checking speed should be valuable whether your Mac is backing up to a local drive, or to network storage, and whether the backup was automatic or manual. It helps to know the normal transfer rate for copying reasonably large files from your Mac to the backup drive, so that you can interpret its results. This can be obtained using a benchmarking utility.

At the top left of a window, set the time period in hours which you want T2M2 to analyse. Do this by editing the number directly, or by using the stepper control next to it. You can enter any period from 1 to 48 hours.

Once that is set, to check backup speeds over that last period, click on the Check Speed button. T2M2 then fetches log entries for the selected period and analyses them. This takes a few seconds: the longer the period you have chosen to analyse, the longer it will take.

During longer backups in Catalina, you should see transfer information given every five minutes. Included in each message is how much has been copied to the backup so far, both in quantity and the number of items, and given in parentheses is the current rate of transfer in MB/s and items/s. At the end of each message is the destination path in the backup which has most recently been copied to.

When the transfer rate falls below 5 MB/s this indicates that backup has slowed to a crawl, and below 1 MB/s it may not finish in acceptable time. Inspect the Last path seen in each entry: they may well have a common path, such as

/Volumes/ThunderBay2HFS/Backups.backupdb/Howard’s iMac Pro/2020-02-12-122530.inProgress/55743950-4FD0-467C-AA23-9EEC158E9685/External1/.DocumentRevisions-V100/AllUIDs/32/com.apple.documentVersions

In that case, the backup is getting stuck copying across items from the hidden folder .DocumentRevisions-V100 on the external drive named External1 . Those folders are a common cause of very slow transfer rates during first full backups in Catalina – a problem which can be fixed.

Save the report as a text file using the Save or Save As commands in the File menu. T2M2 offers a default filename which includes the date and time that the window was opened.

Open as many new windows as you want: each will retain its own report until the window is closed, or it is overwritten by clicking on the Check Time Machine or Check Speed button again.

➜ Fix slow backups

➜ Welcome

The Eclectic Light Company – https://eclecticlight.co