Why is TimeMachine so painfully slow?

[joptimus]

I just don't get it:
I have an Intel MBP2020 and a HS-251 NAS running TimeMachine Service. It includes two 2 TB hard drives.
Network is 5 GHz WiFi with 866 MBit/s (router is 2m in front of me, no walls).

TimeMachine is doing a larger backup (not initial one) of roughly 50 GB. First 35 GB were quite ok, but for the last 15 it calculates 10 hours.
Even at just 100 MBit WiFi speed, that's 10 MB/s. In my book, that's 1500 seconds for 15 GB. Say 1800 - half an hour, not 10 hours.

What is the limiting factor here? I found some toggle to disable throttling of TM: sudo sysctl debug.lowpri\_throttle_enabled=0
Of course I restarted the backup after changing that setting, but it did not help.

I don't understand TimeMachine performance...at all

 

[Fishrrman]

Have you ever considered investigating CarbonCopyCloner or SuperDuper...?

Once my initial backups were done, the incremental backups (using CCC) fly by.
Backing up my boot volume takes about 3 minutes.
Backing up my "main data" volume takes... 5 SECONDS.

 

[joptimus]

Are there any significant drawbacks of CCC versus TM?
I might look into it, thanks for the tip.

 

[BigMcGuire]

Are there any significant drawbacks of CCC versus TM?
I might look into it, thanks for the tip.

TM is baked into Apple's operating system. I have both so I'm a big fan of CCC but ... CCC does require a bit more know how and setup, especially if you want encrypted bootable backups.

TM's speed is horrible but it does make up in ease of use and mostly problem free operation. I've done full system restores with it (that while they took hours, it worked ... perfectly). I've also used it to grab files I accidentally deleted months ago, or a version of a file from weeks back (I keep my TM machine constantly connected).

CCC has a lot of features - including the snapshot like ability of TM. Drawbacks? Costs $, not easy to set up encrypted bootable backup (not CCC's fault)... other than that, it's great. I use it.

 

[Apple_Robert]

Time Machine can be slow at times, because it is busy backing up a lot of system files that have nothing to do with user files.

CCC is a lot faster and you can decide which folders you want to backup.

 

[MacCheetah3]

In addition to what @Apple_Robert said, I think, TM's seemingly slow processing speed is due to organizing and housekeeping as it copies. Primarily intended for selective/incremental restores, keeping files tagged, labeled, what have you, including the many possible versions, is no doubt very tedious.

Even though they can perform incremental backups (for a speedier update) CCC and SuperDuper are more strongly focused on full restores/swaps, thus don't need quite the management TM provides.

 

[BrianBaughn]

One advantage of TM over CCC is the magical "Time Machine" aspect of being able to navigate the past contents of a folder right there in macOS. Another is being able to pick an exact time from which to restore.

I would imagine the vast majority of people who are backing up with TM have never used it and don't know what it can do.

Neither of those reasons is enough for me to use it, though. I do CCC auto-backups of critical drives every night.

 

[bsbeamer]

Even with Time Machine, I still use CCC to cycle and rotate system drive clones and other programmed backups.

Recently have noticed Time Machine becoming increasingly and painfully slow from MBP16,1 to an AirPort connected USB drive. It must have missed any backups for two weeks after an OS update and was prompted. Has been "preparing backup" for 6+ hours so far.

The AirPort is being used in Bridge Mode just for this Time Machine drive since direct USB drive connected to a Linksys router does not work with Time Machine correctly or reliably. Have considered replacing or changing to a WD My Cloud Home drive in the past, but not sure it really would be any faster/better.

Seriously might just connect a portable USB drive to this laptop once a day. If slim fit USB-C flash drives were a thing I'd use that for convenience, regardless of the wear over time concerns (in conjunction with other backups).

 

[panjandrum]

My advice is to use both TM and CCC. TM is extremely slow and unreliable, but also incredibly user-friendly and handy at doing the things that it does well (when it is actually working properly). CCC is a fast, reliable much more capable tech-centric (but still reasonably user-friendly) beast of backup software. It is absolutely worth it to use both.

One big disadvantage to all modern iterations of TM is that it saves "local snapshots" on your primary storage device and eats up your available free space whenever you aren't connected to your TM destination and you have it set to "Backup Up Automatically." I actually use TM in manual mode because of this (I have to tell it to make a backup). CCC, on the other hand, can be scheduled to run automatic backups without spamming your primary storage.

If you can only choose ONE backup method, make it CCC, not TM, for reasons of reliability. I've seen many, dramatic, catastrophic failures of TM. CCC, while less user-friendly, is more likely to come through for you when really needed.

As for the performance? I think the general understanding is that TM is slow by design; so you can hardly tell when it is working in terms of performance impact on the system or the network. CCC, over a network, for example, will absolutely saturate the bandwidth as much as possible unless you manually set a limit. It's a fundamentally different philosophy.

 

[bsbeamer]

Generally speaking, the speed of TimeMachine itself is not my issue. The real issue is the abysmal speed over a wireless connection vs. wired. Had a ~58GB backup from MBP16,1 over wireless that was not finished after leaving the machine on for 7+ days without power down, restart or sleep. It's just not reliable at that point. Plus the added time and frustration of making this almost a desktop doorstop until TM finished.

Just switched to using TM wired via USB-C/USB3-MicroB to a local WD 4TB HDD (Portable My Passport) and TimeMachine is running perfectly fine on MBP16,1. I'll likely switch to using a dock nearly full time with this machine so it can be a single cable connection to power the machine and connect the TM drive at the same time.

I expect a drop in speed for wireless, but when you can copy/write 50GB in less than an hour to network drives there is no excuse for TM taking over a week to complete one stage of a backup.

Never had an issue with TM at all on iMac19,1 to a local USB connected drive.

 

[hoodafoo]

Do people actually run TM backup job and sit there and watch it until completion? Just set it and forget it!

 

[MBAir2010]

are we allowed to back up important files we need on a separate drive without that other systems junk?

 

[Apple_Robert]

Do people actually run TM backup job and sit there and watch it until completion? Just set it and forget it!

Some people watch tv and others like me, watch TimeMachine run.

 

[bsbeamer]

Have noticed an issue with external 5TB+ drives that are being used for Time Machine. Does not matter the brand, model, or connection type. This specifically adds to the slow experience, taking days to complete and often resulting in a corrupted backup that needs to reformat and start from scratch.

Works completely fine as expected with all 2TB, 3TB and 4TB drives, even those formatted "Mac OS Extended (Journaled, Encrypted)" in Disk Utility.

Unsure if this was resolved or addressed in Big Sur. Still on Catalina with all machines, 10.15.7 (19H524).

 

[pnielan]

Some people watch tv and others like me, watch TimeMachine run.

Do people actually run TM backup job and sit there and watch it until completion? Just set it and forget it!

Let's say I want to upgrade my OS---this morning. Best practice; make a few backups using Time Machine and CCC. Just ran Time Machine last night. But have done some work since then. So, ---let's run it again. iMac Pro. Catalina. Direct connect over USB 3 to a 2021 hard drive. Still takes hours for a 10 GB backup. Not upgrading the OS this morning---it's now become a PROJECT. (I do have a 5 GB drive? Is that really a problem as BSBEAMER said?) (CCC backup takes 20+ minutes.)

 

[Apple_Robert]

Let's say I want to upgrade my OS---this morning. Best practice; make a few backups using Time Machine and CCC. Just ran Time Machine last night. But have done some work since then. So, ---let's run it again. iMac Pro. Catalina. Direct connect over USB 3 to a 2021 hard drive. Still takes hours for a 10 GB backup. Not upgrading the OS this morning---it's now become a PROJECT. (I do have a 5 GB drive? Is that really a problem as BSBEAMER said?) (CCC backup takes 20+ minutes.)

I quit using TM. I now use CCC and Arq backup. Both are much faster than TM ever was.

 

[T-R-S]

I use both neither are perfect - TM takes forever My 2020 MB Air initial took 4 days with a fast USB3 drive. Apple changed my motherboard I had to do a restore it took 5 hours. Then because of the Motherboard it seems to want to start from scratch. I had a CCC backup as well but now with the T2 chips I can’t seem to figure out CCC system back up - but truth be told I spent zero time trying to figure it out. I hated TM restores Permissions in my Users folder were totally messed up. TM restored months old Data instead of last back up. CCC to the rescue. In brief neither are perfect in order to have a legit reliable back up - you need to use both. But I am Strictly speaking about your system drive.

 

[tuckerdogavl]

Have you ever considered investigating CarbonCopyCloner or SuperDuper...?

Once my initial backups were done, the incremental backups (using CCC) fly by.
Backing up my boot volume takes about 3 minutes.
Backing up my "main data" volume takes... 5 SECONDS.

Why is the answer to buy something else? Let's go back to the original question. My MacMini has been backing up for years and pretty fast. Since updating the OS to Monterey 12.6.2. It takes about four hours to do incremental backup.The "initial" backup was close to 1TB. Currently it's at 80% of 850mb... for 2 1/2 hrs. Wait.... 80.2% done.

 

[name99]

I just don't get it:
I have an Intel MBP2020 and a HS-251 NAS running TimeMachine Service. It includes two 2 TB hard drives.
Network is 5 GHz WiFi with 866 MBit/s (router is 2m in front of me, no walls).

TimeMachine is doing a larger backup (not initial one) of roughly 50 GB. First 35 GB were quite ok, but for the last 15 it calculates 10 hours.
Even at just 100 MBit WiFi speed, that's 10 MB/s. In my book, that's 1500 seconds for 15 GB. Say 1800 - half an hour, not 10 hours.

What is the limiting factor here? I found some toggle to disable throttling of TM: sudo sysctl debug.lowpri\_throttle_enabled=0
Of course I restarted the backup after changing that setting, but it did not help.

I don't understand TimeMachine performance...at all

A few years ago Apple added QoS (quality of service) support to IO requests, so that less important IO could be delayed relative to more important IO. Naturally Time Machine runs at a low QoS. For years this did not matter until recently (maybe two years ago?) Apple actually hooked up these IO QoS APIs to working code, and the code started implementing the the QoS.
I think it's not at all understood quite how Apple implements the throttling, and it seems to have changed a lot over successive OS releases. I don't have a NAS but I do implement backups to both local hard drives and via network to a "storage server" mac with hard drives. My experience was that for the first six months or so after this change backups were REALLY slow, apparently because it's hard to implement QoS for a hard drive (any time I move the head for my tasks, it hurts your tasks, and hurts a LOT) so Apple seemed to be very aggressive in not allowing Time Machine much disk access if there was any other activity going on. But after six months or so Apple seems have fixed the worst of this, with things getting even better in the next OS release. So for MY use cases, it's no longer an issue.

For you I'd say
- are you running the latest version of macOS? Bug fixes in this area have made a huge difference.
- if you are running the latest version, I'd say it's worth reporting this via feedback.apple.com. Often feedback seems to disappear into a back hole, but this was one case where the people involved really wanted to get it right. But it may be that, while they got the IO QoS details correct for the cases I care about (local hard drives, ethernet attached remote hard drive speaking SMB and using APFS) they may not have got them right for your case (WiFi? NAS? using AFP rather than SMB?)

A SEPARATE issue (and don't confuse the two) is the SCHEDULING of backups. This is done by CoreDuet, a subsystem that tries to execute background tasks when the machine looks like it is less busy than usual (rather than exactly every hour on the hour, or whatever). CoreDuet usually works well, but will seem like it is "doing it wrong" if you are obsessively looking for Time Machine to start on a specific schedule...

 

[name99]

Why is the answer to buy something else? Let's go back to the original question. My MacMini has been backing up for years and pretty fast. Since updating the OS to Monterey 12.6.2. It takes about four hours to do incremental backup.The "initial" backup was close to 1TB. Currently it's at 80% of 850mb... for 2 1/2 hrs. Wait.... 80.2% done.

Can you not move to Ventura?
I can't remember the details of which version of the OS fixed this substantially (as I described in my previous post) but it is pretty much completely fixed for me in Ventura).
Obviously it sucks when Apple ships a bug in the OS, bug this is one where they seem to have made an effort to fix the problem once they figured out where and when it occurs.

 

[PhoneandPad]

Have noticed an issue with external 5TB+ drives that are being used for Time Machine. Does not matter the brand, model, or connection type. This specifically adds to the slow experience, taking days to complete and often resulting in a corrupted backup that needs to reformat and start from scratch.

Works completely fine as expected with all 2TB, 3TB and 4TB drives, even those formatted "Mac OS Extended (Journaled, Encrypted)" in Disk Utility.

Unsure if this was resolved or addressed in Big Sur. Still on Catalina with all machines, 10.15.7 (19H524).

Interesting. Mine is backing up to a 5TB WD drive. It's the first time I've backed up since about 6 months ago. It took several hours to calculate 22 hours as the time to do the backup. At the snails pace it's going, looks more like 36 hours. I used to back up to a 2TB Toshiba drive, however Time Machine kept saying not enough space. Seems that if you have a main Mac drive 2TB in size, it needs a lot more for the Time Machine drive.

To those who say they just leave their Time Machine drive connected all the time and forget about it, it looks unsightly but more importantly, any catastrophic failure of the Mac e.g. water damage or a voltage surge, could kill both the internal and Time Machine drive at the same time. Everyone knows that backups should be stored securely away from the PC itself.

 

[Apple_Robert]

TM has always been slow. That, in and of itself doesn't really vex me. What vexes me if the fact that it doesn't properly check the backup for corruption. And if the backup is corrupt, the user won't know it until he or she attempts to use said backup. At that point, TM will let the user know that the backup is corrupt and can't be used to restore the Mac.

With Carbon Copy Cloner and other backup programs, that kind of thing doesn't occur. If there is a problem, these other programs will let the user know right away if there is a problem initiating or finishing the backup etc.

 

[zevrix]

any catastrophic failure of the Mac e.g. water damage or a voltage surge, could kill both the internal and Time Machine drive at the same time. Everyone knows that backups should be stored securely away from the PC itself.

Agree. That's why, in addition to Time Machine, ideally we also need to run an online backup service. I'm using CrashPlan, and there are other also available.

 

[PhoneandPad]

TM has always been slow. That, in and of itself doesn't really vex me. What vexes me if the fact that it doesn't properly check the backup for corruption. And if the backup is corrupt, the user won't know it until he or she attempts to use said backup. At that point, TM will let the user know that the backup is corrupt and can't be used to restore the Mac.

With Carbon Copy Cloner and other backup programs, that kind of thing doesn't occur. If there is a problem, these other programs will let the user know right away if there is a problem initiating or finishing the backup etc.

Useful to know. I'm planning to use OCLP to update the old Mac to Ventura. Didn't want to experiment on the working bootable drive so bought a 2TB external USB drive. Installed Mojave on it, booted this then restored all the data from the TM drive. This worked well and proved the old TM backup was good. Think I'll test the latest TM backup in the same way before deciding the TM doesn't need redoing.