SSD as Backup Drive?

[dix]

Oh, my. I hope you remain safe HC! Jeez, what a year

When I fill a Time Machine drive, it gets retired and stored. It takes quite a while to fill 8TB.

I can't find a solid answer anywhere on how long a new 10tb backup would take with Time Machine. If I were to un-throttle TM would it be the same speed as whatever USB 3.0's data transfer rate is (my TM drive is on a USB3 bus)? And how long throttled?

[MIDI Life Crisis]

Oh, my. I hope you remain safe HC! Jeez, what a year

When I fill a Time Machine drive, it gets retired and stored. It takes quite a while to fill 8TB.

I can't find a solid answer anywhere on how long a new 10tb backup would take with Time Machine. If I were to un-throttle TM would it be the same speed as whatever USB 3.0's data transfer rate is (my TM drive is on a USB3 bus)? And how long throttled?

It's not how long a new 10TB drive will take to backup, it's a matter of how much data you'll be putting on it. But the time it takes is irrelevant. It will take as much time as it needs, but it will do that in the background. You won't need to stop using the machine.

[dix]

8-9ish TB is how much I'd like to backup. I'm planning on getting a 14tb drive.

I'm probably overthinking and paranoid, but while TM is creating the new backup (several days throttled) am I not vulnerable during those several days? After two days of TM creating the new backup, my most recent backup, on the retired drive, would be two days old...no?

[MIDI Life Crisis]

The first backup will take a while (probably not days but certainly several hours). After that, only the most recent versions of files will be backed up. Magic!

As far as being vulnerable, your current backup will still be on the drive, unless you're not backed up now. In which case, you're vulnerable now.

[dix]

A straight transfer of that much data might only take several hours (although my experience is that it'd take most of a day), but a throttled TM backup could easily take days. Un-throttled would suck a noticeable amount of resources.

To be clear, you don't transfer the current TM document to the new drive when retiring the old TM drive do you? What is the procedure for starting a new Time Machine backup? Simply unplugging the old TM drive and telling TM use the new one is my assumption.

[MIDI Life Crisis]

I don't know what you mean by throttled. No, DONOT copy the TM backup to the new drive. Go to the TM system preference and add the drive. If there's a current drive, leave it in place. That's you redundant drive. If not, just start the backup. No need to remove the old backup. Once the new backup starts it will go until completion. AFAIK, there is very little CPU hit but I've never checked. It's straight forward data transfer. It does not impede using the machine, and visa versa. Just chill. Turn it on and forget it until the backup is complete.

[dix]

By design TM throttles transfer speeds to keep resource usage minimal. It can be defeated with a Terminal command for faster backups, at the expense of resource conservation.

I see...maybe. So once Time Machine sees the new TM drive the round-robin will start backing up everything to that drive until there's a full (in my case 9tb+) backup on the new drive, before trying to create a redundant backup on the old TM drive? At what point in this process do you yank the old TM drive for retirement?

Thanks again

[MIDI Life Crisis]

Once I have two backups, I wait a week or two with the old drive on a shelf. When you’re confident your new drives are backing up correctly you can either wipe the old drive or hang onto it. I generally wipe them after about a month or so. No rush. Drive space I got. In total probably about 20+ TB across all drives.

[mikehalloran]

At what point in this process do you yank the old TM drive for retirement?

When you are confident it's no longer needed.

When TM drives get full, the oldest backups are deleted. They never stop accepting new backups.

I have a box of old TM drives—every one has passed SMART 100%. One of the 6TB Reds and the 3TB Green I pulled will go into it while I'll sell the other two 6TBs. The two drives I'm saving have backups of my daughters' Macs as well. You just never know.

I've had a much bigger box of HDDs with SMART tests that look more like this:



Those do not get kept.

[HCMarkus]

Oh, my. I hope you remain safe HC! Jeez, what a year

Thanks dix. Threat has subsided here, but not for others, What a year, indeed!

[HCMarkus]

WD appears to be having communications problems as of late... first it was SMR, now RPM:

https://arstechnica.com/gadgets/2020/09 ... -word-rpm/

Last week, the fine Redditors of /r/DataHoarder got upset with Western Digital again—this time, for misrepresenting the rotational speed of their WD Red Network Attached Storage hard drives...
We found this controversy reminiscent of earlier complaints that Western Digital was not properly disclosing use of Shingled Magnetic Recording technology in their NAS drives. But the new complaint is that Western Digital calls 7200RPM drives "5400 RPM Class"—and the drives' own firmware report 5400 RPM via the SMART interface.

[dix]

Finally got a new, big ol' 14TB drive for Time Machine backups. TM is giving me a choice

Do you want to stop backing up to “WD 6TB BU” and use “WD 14TB BU” instead, or back up to both?

If I want to "retire" the 6TB I'd choose "use 14TB instead" presumably (and the "both" option for round-robin presumably).

Am I correct in assuming that whatever is on the 6TB, when I make the choice, will serve as the only TM backup of my OS until the new backup on the 14TB is complete? Or does Time Machine prioritize and backup the OS first so I have access to Time Machine for the OS before the entire backup is complete? I'm guessing an entirely new TM backup will take a week or so.

[mikehalloran]

(and the "both" option for round-robin presumably).

You presume correctly.

Am I correct in assuming that whatever is on the 6TB, when I make the choice, will serve as the only TM backup of my OS until the new backup on the 14TB is complete?

Yes but…

If you quit that backup for any reason including rebooting or the drive shuts down during sleep, it will go to the other drive next. Then it will attempt to complete that first backup an hour later. Enabling Power Nap in the System Preferences/Energy panel will keep a TM backup going through the night.

This will continue until that first backup is completed on the 14TB — however long that takes — and then they will alternate in the normal fashion.

Since High Sierra, the first thing that TM does is write a new Snapshot to the System drive. Every time.

[HCMarkus]

If you are worried about backing up during the initial TM run, you can always do a manual backup of critical work. That's what I do every day for projects I'm working... I copy the project folder to two spinners at the end of every session, merging the data if I am backing up a project that had been backed up previously.

[dix]

It's just the Time Machine back-in-time functionality that I'm wondering how long I'd be without. I'll have my normal Backblaze backup and daily manual backups of projects. Plus I'll do regular CCC clones (sry mike!) while TM is doing its thing. I should be good. ...TM estimates just 21 hours until it's all done, which is less than I anticipated.

Thanks all!