How can I test the speed of my external Time Machine drive?

[davidg4781]

I've been using an older WD My Passport for Time Machine. I was using the included USB 3.0 cable through Apple's adaptor (USB A, USB C, HDMI).

I bought a micro B to USB C cable on Amazon and want to see if it'll be faster but Blackmagic won't let me choose it since it's classified as Read Only. It doesn't look like I can change the permissions on this drive either.

Any ideas? Can I do a TM backup and check Activity Monitor?

 

[Bigwaff]

With the WD My Passport connected using the micro B to USB C cable, launch Disk Utility. On the left, select the volume with your Time Machine backups. In the table on the right, what is the "Type" ?

 

[davidg4781]

With the WD My Passport connected using the micro B to USB C cable, launch Disk Utility. On the left, select the volume with your Time Machine backups. In the table on the right, what is the "Type" ?

I downloaded iStat Menus, it peaked at 54M. I'm trying it again with the Apple adaptor and saw your post.

The Type in Disk Utility is APFS Volume.

 

[MarkC426]

A Time Machine drive cannot be tested with BM Utility (or similar), just checked myself.
AJA system test says you need to change permissions on the drive to enable write.

I wouldn't mess with this.
What are you concerned about, are your backups really slow?

 

[gilby101]

I bought a micro B to USB C cable on Amazon and want to see if it'll be faster but Blackmagic won't let me choose it since it's classified as Read Only. It doesn't look like I can change the permissions on this drive either.

The TM volume is read-only (except for TM doing a backup). But you can add another APFS volume to the APFS container/partition on the physical drive. Make sure Disk Utility has View > Show All Devices enabled, select the container and add a volume. That volume will be read/write.

But you will probably find that Blackmagic reports very poor performance. This is in part because the HDD is a relatively slow SATA drive and partly because disk speed tests are best done on an empty unfragmented drive.

 

[MarkC426]

I've been using an older WD My Passport for Time Machine. I was using the included USB 3.0 cable through Apple's adaptor (USB A, USB C, HDMI).

Unless you are creating huge files hourly, a HDD TM should be fine, as it's all incremental.
If your TM drive is getting full, it will slow down.

What size drive are you backing up, what size is the TM drive?

 

[benwiggy]

TM is a background process, that doesn't have any speed requirement. As long as you can get the backup done within the hour before the next one, you're good.

Of course, if you have to restore the whole thing, then you want a fast drive.

Nearly all hard drives are still SATA, so 600 Mbps tops.

 

[Killroy]

TM is a background process, that doesn't have any speed requirement. As long as you can get the backup done within the hour before the next one, you're good.

Of course, if you have to restore the whole thing, then you want a fast drive.

Nearly all hard drives are still SATA, so 600 Mbps tops.

SATA specs out at 6Gbps. Time Machine use APFS which is not good for mechanical hard drives.
It's best to use an SSD drive because time machine APFS is now the standard used by Apple.

 

[davidg4781]

A Time Machine drive cannot be tested with BM Utility (or similar), just checked myself.
AJA system test says you need to change permissions on the drive to enable write.

I wouldn't mess with this.
What are you concerned about, are your backups really slow?

I was mainly trying to get rid of the dongle and just connect the drive straight to the MBP. I couldn't find a normal brand I would use and just got some brand from Amazon that had a lot of good reviews. But after I received it, I was just wondering if there are any performance gains or losses from using that off brand cable than the original WD cable through Apple's dongle.

Unless you are creating huge files hourly, a HDD TM should be fine, as it's all incremental.
If your TM drive is getting full, it will slow down.

What size drive are you backing up, what size is the TM drive?

It's a 1 TB drive. I've had it since 2014. The important stuff is backed up to iCloud and I keep a local backup of everything. I know it's getting old and probably should be replaced but I haven't had any issues and hopefully shouldn't have a failure of this AND the MBP at the same time.

SATA specs out at 6Gbps. Time Machine use APFS which is not good for mechanical hard drives.
It's best to use an SSD drive because time machine APFS is now the standard used by Apple.

Interesting. I may look into SSD prices. I'd like to have a TM backup that's on the network instead of having to plug one in.

 

[MarkC426]

It's a 1 TB drive. I've had it since 2014. The important stuff is backed up to iCloud and I keep a local backup of everything. I know it's getting old and probably should be replaced but I haven't had any issues and hopefully shouldn't have a failure of this AND the MBP at the same time.

What percentage of your Mac drive is used (and size)?

 

[davidg4781]

What percentage of your Mac drive is used (and size)?

1 TB SSD in my MBP, about 50% used.

I know I should have a 2+ TB TM drive but this is what I have. If I start using more of my internal drive, I'll start looking at larger storage solutions, preferably a NAS.

 

[HDFan]

It's best to use an SSD drive because time machine APFS is now the standard used by Apple.

Not really. SSDs for TM are overkill as you don't need the speed since backups run in the background. You can also afford a larger HD which increases your TM history. Exceptions do exist for harsh environments, etc.

 

[Killroy]

But what you don't get is the robustness of Snapshots taken with the APFS format.
With APFS on a hard drive you get a progressive slowdown as the drive fills up with more work to do. You only get Journaled directories with HFS+.

 

[ignatius345]

It's a 1 TB drive. I've had it since 2014. The important stuff is backed up to iCloud and I keep a local backup of everything. I know it's getting old and probably should be replaced but I haven't had any issues and hopefully shouldn't have a failure of this AND the MBP at the same time.

Interesting. I may look into SSD prices. I'd like to have a TM backup that's on the network instead of having to plug one in.

You can buy a 1TB SSD for next to nothing at this point. If you're OK shopping Amazon this page is very helpful: https://diskprices.com/

Avoid SanDisk Extreme, though: https://arstechnica.com/gadgets/202...e-worthless-multiple-lawsuits-against-wd-say/

 

[davidg4781]

You can buy a 1TB SSD for next to nothing at this point. If you're OK shopping Amazon this page is very helpful: https://diskprices.com/

Avoid SanDisk Extreme, though: https://arstechnica.com/gadgets/202...e-worthless-multiple-lawsuits-against-wd-say/

Interesting about SanDisk.

I used to always use WD, but the last time I bought one was 2017 and I think that was for my PowerMac G5 that's been sitting in my closet the last 7 years.

 

[HDFan]

But what you don't get is the robustness of Snapshots taken with the APFS format.
With APFS on a hard drive you get a progressive slowdown as the drive fills up with more work to do. You only get Journaled directories with HFS+.

TM on a hard drive will reformat the drive as APFS. Again since TM backups occur in the background speed is normally not an issue. I run multiple TM backups on APFS formatted hard drives with no problems.

 

[Killroy]

TM on a hard drive will reformat the drive as APFS. Again since TM backups occur in the background speed is normally not an issue. I run multiple TM backups on APFS formatted hard drives with no problems.

That's just you not every body's setup. I run TM on a Raid 5 volume APFS. that way if a drive dies I do not lose any data because it's rebuilt from the spare drive.

 

[HDFan]

if a drive dies I do not lose any data because it's rebuilt from the spare drive.

If the volume (pointers) gets/get corrupted then a rebuild isn't going to fix the problem. A rebuild of a RAID 5 volume when a disk fails and you have a corrupted TM backup is just going to give you another corrupted TM backup.

 

[Killroy]

If the volume (pointers) gets/get corrupted then a rebuild isn't going to fix the problem. A rebuild of a RAID 5 volume when a disk fails and you have a corrupted TM backup is just going to give you another corrupted TM backup.

Man, you must be using a very unreliable raid system.

 

[HDFan]

Man, you must be using a very unreliable raid system.

It's not a RAID issue (I have quite a few), it is a TM issue. If the TM file gets corrupted in some way, which does happen, then there is nothing that a RAID configuration can do to fix it. RAID protection is invoked when a disk fails. It doesn't know if a specific file looks good but has been internally corrupted, such when TM has written bad pointers.

RAID 5 provides disk level protection. It does not provide protection for files which have been internally corrupted.

 

[Killroy]

It's not a RAID issue (I have quite a few), it is a TM issue. If the TM file gets corrupted in some way, which does happen, then there is nothing that a RAID configuration can do to fix it. RAID protection is invoked when a disk fails. It doesn't know if a specific file looks good but has been internally corrupted, such when TM has written bad pointers.

RAID 5 provides disk level protection. It does not provide protection for files which have been internally corrupted.

The one have does. It checks all data against parity, and the drive does not have to failed for the check to be done periodically that prevents bit rot. Drives are flagged for errors long before
they fail. Single drives used for TM run the risk platter damage, bit rot and servo failure.
The figures I have come across by peoples hard drives that are dropped or do not unmounted before disk disconnecting.

TM gives you a chance to roll back just before error with a snapshot so if you can read the last snapshot you may get your data back.

 

[HDFan]

A parity check is not going to find a TM problem if an internal pointer is corrupted but the file is ok. You can't roll back if the TM image is internally bad and TM fails.

Maybe you will be lucky. I certainly haven't.

 

[Killroy]

A parity check is not going to find a TM problem if an internal pointer is corrupted but the file is ok. You can't roll back if the TM image is internally bad and TM fails.

Maybe you will be lucky. I certainly haven't.

Try the app "Disk Drill".

 

[bogdanw]

As it hasn't been mentioned so far, Cross Platform Disk Test (CPDT) https://github.com/maxim-saplin/CrossPlatformDiskTest

 

[HDFan]

Try the app "Disk Drill".

That might help with file corruption. Won't help when TM writes a pointer with the wrong values to a file. The classic resource for understanding the Unix file system (before APFS) is:

The Design of the UNIX Operating System

The Design of the UNIX Operating System

www.amazon.com

Here's a brief discussion about Time Machine internal structures:

Time Machine to APFS: Backup structure and access

Unlike HFS+ backups, those on APFS volumes look different depending on how you try to access them. What you see in the Finder is an illusion not available to other apps.

eclecticlight.co