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I know that Windows 2008 R2 and 2012 were limited to 2TB volumes (or at least the size of files) due to the fact that internally Windows Server Backup uses VHD files which are limited to ~2TB.

I can't find anything in the docs from MS regarding 2012 R2 and whether internally WSB uses VHDX instead, bumping the limit up to 64TB. We're looking to backup a few volumes with ~4TB per volume. I'd hate to have to go and reallocate them just to get backups working.

MS has to know that people have backup needs for volumes larger than 2TB, right?

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YES. –  the-wabbit Jan 9 at 21:53
My bad -- I didn't exactly leave the post with a real question. I should have ended it as "Does Server 2012 / 2012 R2 still use VHD internally for backups, or has Microsoft moved to VHDX?" –  a.t. Jan 9 at 21:59
If you break it up in two questions, then: No. Yes. –  the-wabbit Jan 10 at 8:08

2 Answers 2

Hm. ANother one bites the dust....

I know that Windows 2008 R2 and 2012 were limited to 2TB volumes

They were not. Only for MBR discs. Not for GPT diss.

See also:


Pretty much every company these days likely has larger paritions. 2tb are not relaly large when you get larger discs. But then, the problem really in your case is more what you think you know - not the facts.

Change to GPT partitions and there you are.

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Andrew was referring to the limitation in the .vhd virtual disk format, which, in fact, is 2 TB. Since Windows Server Backup has been using .vhd files as backup destinations, it was subject to this limit. In Server 2012 the Server Backup uses .vhdx, the new limit is 64 TB. –  the-wabbit Jan 9 at 21:51
Thanks syneticon-dj. TomTom, I'm aware of MBR vs GPT. In fact, the only way I have volumes larger than 2TB is by initializing the disk as GPT. As syneticon-dj noted, WSB was limited to the VHD size of 2TB, regardless of the disk's partitioning scheme. I didn't realize the change was made in 2012 -- for some reason, I thought I was still running into that issue using 2012. –  a.t. Jan 9 at 21:56
That may not be an issue though - you could split a backup on multiple VHD theoretically. THat said, seriously, I expect many companies having larger data to simply use a more mature backup product ;) –  TomTom Jan 9 at 22:05
@TomTom 4 TB is not what counts as "larger data" anymore. It is commodity. And a small business "CEO" with 2 underpaid employees and a $500 "server" under his desk certainly would think really hard before purchasing software which requires a separately licensed backup agent for every imaginable application type. But as I noted, it has been addressed already. –  the-wabbit Jan 10 at 8:04
But 2008 R2 is also not a current operationg system anymore. THat makes your argument circular. Especially given that your CEO is much more likely to make backups by making copies to a USB disc in the real world. –  TomTom Jan 10 at 8:27

I have trouble finding authoritative references either, this blog post claims:

The VHDX format allows for 64TB. That means your Windows Server backup can now handle more than 2TB LUNs. This should be adequate

It should be easy enough to verify by just doing a WSB run on a Windows Server 2012 (R2) host and looking at the result.

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as an aside: as tempting as it seems to do backups to an NTFS-compressed destination, it would need some work to actually succeed. NTFS compression is FUBAR for large files by default. –  the-wabbit Jan 10 at 8:24
agreed. i rarely use it, although i'm planning to start using deduplication much more heavily going forward for new file servers since 2012 R2 seems to be more robust. –  a.t. Jan 11 at 2:41

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