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Maximum drive size for Time Machine?

I

ispcolohost

macrumors member
Original poster
Nov 28, 2017
39
36
Hey all, I was researching some Time Machine target solutions to give me a much longer retention time, as I have about 6 TB of data and a change of data of about 1 TB per week, so an external 8tb drive only gives me three weeks of weekly backups at this point. I was thinking about throwing a NAS on my network to be a Time Machine target, but then saw this Synology article which suggests Time Machine can't use volumes larger than 16 TB:

https://www.synology.com/en-global/...to_backup_onto_shared_folders_exceeding_16_TB

Anyone have recent experience trying to use a large NAS target for Time Machine? I was thinking I'd throw 48 TB in and then I could simply set Time Machine back to auto and let it do its thing hourly with months of backups. If it wouldn't be able to use all the space though that obviously complicates matters.
 
I've no idea if the 16GB limit is still true. That article was written for OS 10.7.

The WD My Cloud series of NAS drives include Time Machine as a default setting. They have phone support so you might want to have a pre-sales talk with them before purchase.

Although they default to RAID 1, you can configure them as you like — mine are set up JBOD. The stated capacities are up to 40TB— 10TB per platter —but that's old news from back when the Red was 10TB max — now it's 12
https://www.wd.com/products.html

These are loaded with the Red, an extra heavy duty HDD designed for oversized bearings for 24/7 cool running. A Seagate employee gave me the heads-up on these. I've never had one go down.
https://www.wd.com/products/internal-storage/wd-red.html#WD120EFAX

I also like that they're ethernet. No wake from sleep issues ever. Although relatively quiet, they're not perfect so I keep mine in a different room.

That you need a drive larger than 8TB makes sense but I don't understand why you need larger than 16TB.

For example, I have over 2TB of virtual instruments (VIs) and my iTunes library is well over 300GB. By archiving every time I make any real change every few months, I keep them out of my TM backup. Even if disaster were to happen, I can re-download everything. Since I keep those files on an external anyway, excluding them from TM is easy.
 
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On a semi-related noted costco.com and our local store has Seagate 8TB Backup Hub on sales for $120.
 
From another thread I just learned Time Machine can use more than one drive, so worst case I think I could create more than one 16TB volume to work around the issue. The reason I want 16+ is to just have more and more roll back points since I have about a TB of data change per week, so at 16 I'd have enough for the 8TB base but depending on how much data changes per hour, I may only fit a few more weeks of retention in before hitting the limit.
 
priitv8 said:
You could extend your backup capacity even more with the Time Machine Editor to leave bigger than default 1h gaps between individual backup runs.
Click to expand...

Ah this sounds great, will be going that route. I don't need hourly.
[doublepost=1566289844][/doublepost]
mikehalloran said:
What exactly do you mean by that?
Click to expand...

Of my 6-8TB of raw data that I back up, about 1 TB of it changes every week, meaning if I were doing solely once per week Time Machine backups, where Time Machine backs up only the changed data, it would be adding an additional 1 TB of new data per week. The Time Machine Editor someone posted should help reduce what goes in the backup set quite a bit, as backing up a few times per week is sufficient for me to not lose anything greatly important, and will reduce the size of those delta (changes since the full or previous) backups.
 
ispcolohost said:
Ah this sounds great, will be going that route. I don't need hourly.
[doublepost=1566289844][/doublepost]

Of my 6-8TB of raw data that I back up, about 1 TB of it changes every week, meaning if I were doing solely once per week Time Machine backups, where Time Machine backs up only the changed data, it would be adding an additional 1 TB of new data per week. The Time Machine Editor someone posted should help reduce what goes in the backup set quite a bit, as backing up a few times per week is sufficient for me to not lose anything greatly important, and will reduce the size of those delta (changes since the full or previous) backups.
Click to expand...
You haven’t answered my question.

What kind of data changes 1G completely every week?
 
I know this doesn't have to do with the OP's question about maximum capacity, but I just wanted to say a few years ago I purchased a second OWC Thunderbay 4 Raid populated with 4 3TB hard drives in a RAID 5 just for Time Machine, and the improved speeds are much appreciated. I don't think I could ever go back to the incredibly slow single HD backups. Hoping to switch to all SSDs when they come down in price a bit more but this works quite well in the meantime.
 
It's a bit off topic, but I wonder if Time Machine is the "correct" way to back up here. It seems you have a huge "data set" in addition to your system disk. Why not back that up separately?

Time machine works great (well, most of the time...), but it's hardly a solution for data centers.

So if your big data is easily separated, I'd look for two different backup strategies here.
 
mikehalloran said:
You haven’t answered my question.

What kind of data changes 1G completely every week?
Click to expand...

I didn't answer it because I don't see where you asked such a question. You stated you agreed I'd need more than 8 but did not understand why I wanted more than 16. I explained it was due to my desire for longer retention times than could be accommodated given my rate of data change. You stated you did not understand what I meant about 1tb of data changing per week. I explained again.

If you're simply curious, it's a bunch of vmware fusion virtual machines running mostly linux. I need to test software builds that deploy to a large number of supported operating system versions and configurations, which is quite easy if all the vm's are running on my own computer with a shared drive they can pull the packages from. Once all that occurs, the underlying changes to these guest operating systems amounts to what can be as much as 1tb of data changing in a given week.

I like Time Machine because it's a mostly set it and forget it option, I don't have to think about excluding my vmware directory and then copying out vmdk's to some other storage.
 
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