Version 9.5.2 Released Today

In recent days my Time Machine backups have been very slow. After some experimentation, I think it is related to Sophos.

I have a USB3 WD Passport, encrypted. My main HD (MBP, SSD, El Cap) is also encrypted. The TM drive is on the Sophos excluded list.

Time Machine will start, but will backup about 1.9 MB in 30 minutes.

If I turn off Sophos, the backup runs at the normal rate (~ 5Gb in 10 min).

Are there any logs I can collect for Sophos to trouble shoot? My gut tells me it is related to the internal SSD in the MBP, not the external TM, but I cannot be sure.

In recent days my Time Machine backups have been very slow. After some experimentation, I think it is related to Sophos.

I have a USB3 WD Passport, encrypted. My main HD (MBP, SSD, El Cap) is also encrypted. The TM drive is on the Sophos excluded list.

Time Machine will start, but will backup about 1.9 MB in 30 minutes.

If I turn off Sophos, the backup runs at the normal rate (~ 5Gb in 10 min).

Are there any logs I can collect for Sophos to trouble shoot? My gut tells me it is related to the internal SSD in the MBP, not the external TM, but I cannot be sure.

I have noticed the same issue with TM backups and the upgrade to Sophos 9.5.2.

I leave Time Machine’s automatic backup off. I initiate a manual backup (Back Up Now) normally once a day when any work files have largely been saved to disk. The typical daily backup amounts to 2GB or less and has, for years, generally taken a couple of minutes at most with the backup “Count-Up” display moving pretty quickly, jumping many MB’s at a time.

Starting immediately after the upgrade to Sophos 9.5.2, the time required to backup has grown substantially and the backup speed has dropped sharply especially at the beginning of the process with progress registered in KB's rather than MB's. It’s as if many very small files are being processed with much more “attention” than previously since what’s getting backed up hasn’t changed much except, perhaps, for what the 9.5.2 upgrade has introduced.

Activity Monitor doesn’t show anything special going on. And Time Machine is on a different HD on the same SATA bus as the boot SSD.

However, starting a manual backup just now with Sophos On Access scanning on runs very slowly (actually showing bytes for the first time ever); turning it off during the process speeds it up noticeably, and turning it back on slows it down again.

Same here with Time Machine now very slow since V9.5.2.

Both for a networked Time Capsule and USB3 attached drive.

Backups are MANY times faster with Sophos on-access scanner turned off.

Also, for many months now I've rarely been able to burn a DVD successfully with Sophos on. I haven't explored it thoroughly, as I also turn Time Machine off as well, and just get on with it. With just Time Machine off, DVD burning still fails. I haven't tried with only Sophos on-access scanning and/or auto-updating turned off.

We identified an issue which causes slow Time Machine backups, and our next release should include a fix.  In the mean time, you can disable background process throttling in order to speed up your backups:

sudo sysctl debug.lowpri_throttle_enabled=0

William

litanyww said:

We identified an issue which causes slow Time Machine backups, and our next release should include a fix.  In the mean time, you can disable background process throttling in order to speed up your backups:

sudo sysctl debug.lowpri_throttle_enabled=0

William

Since disabling background process throttling via that command appears to be permanent (at least until the next release), what would we be giving up?

And can I assume that setting enabled=1 will turn it back on? I normally I just turn On-Access Scanning off during the TM backup but the Terminal command is quicker.

I don't know what "background process throttling" is?? Is this the same as on-access scanning?? Please advise.

The key question is when you expect to release a fix for Time Machine problem. An estimate, even though not guaranteed, would be very helpful. Please advise.

hellohgjytrjytr said:

I don't know what "background process throttling" is?? Is this the same as on-access scanning?? Please advise.

The key question is when you expect to release a fix for Time Machine problem. An estimate, even though not guaranteed, would be very helpful. Please advise.

I don't know what "background process throttling" is either though I suspect it involves favoring current activity performance over the stuff going on under the hood (probably such as Sophos On-Access Scanning which is why the throttling is set to off), and since the setting appears more general than just Sophos-related, I'm concerned what other  processes might be affected by turning background throttling off.

Please note that I'm just a Sophos user like you, not an expert and don't know when the fix will be released either, though I suspect it'll be when it's ready, unlike, seemingly, macOS Sierra.[;)]

Update: Some researching resulted in more information about background process throttling. This link provides a discussion and some cautions regarding such throttling. Personally, I'll wait for the Sophos update and just turn off On-Access Scanning only when running a TM backup (that's one of the advantages of running TM manually as needed rather than automatically).

Regarding TM backups and the recent slowdown with On Access scanning running, I’ve been noticing that while the projected run time can get to be pretty long, as the backup progresses, the speedup can be considerable.

Note that I have automatic backups turned off and initiate the backup manually. With the TM window open, the progress, especially the jumps in data processed, improves over time. This doesn’t happen all the time and is most likely when the backup runs over 5GB. It’s as if the Sophos process stops qualifying as “background” if a certain quantity of data is surpassed.

I'd noted that earlier in the week, the Sophos update download that I initiate when I boot up was 4.5MB rather than the usual KB, suggesting that more than just signature files were being updated but the Sophos version number hasn't changed. Turning On-Access Scanning off still speeds up the backup immediately but the speedup does seem to occur when enough has been already backed up. It's possible that TM arranges data by size for backup with the largest files last but that's just a guess, though it would explain what I've observed.

An update: Just tried it again and with a 6.5GB TM manual backup, the estimated time grew to 40 minutes. Then, with about 4GB done (I wasn't staring at it constantly since about 15 minutes had dragged by), it abruptly dropped to 4 minutes and then took about one minute to complete. On-Access Scanning was on for the full period.