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i'm using Windows 7

i just lost a .vdi file (a virtual hard drive for my VM) i'm wondering if there's a file size limit for windows which might have caused a problem, i hadn't checked the size of the file lately (i set it to dynamically size as needed), but it was 15 to 30Gb at a guess.

it wouldn't back up using windows back up, but is it possible windows has just stopped recognising it because it's too big? Is there a clear upper limit on file size?

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By the way - if somebody has provided an answer which solved your problem, please mark it as accepted by ticking the check mark next to that question. It looks like you have asked a lot of useful questions, but you haven't marked very many of them as answered. A higher acceptance rate encourages users to continue answering your questions, and helps the community know which questions are still unsolved, and which have already been dealt with. Thanks! – nhinkle♦ Dec 15 '10 at 7:51
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2 Answers

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If the drive with your file is formatted with NTFS (which is the default in Windows 7), then according to Wikipedia, the maximum file size is 16 TB. Even if you were to (attempt) to exceed that limit, you would simply be unable to make the file any larger. It might lead to some strange behavior in VirtualBox, but would not cause the file to disappear.

What exactly do you mean by "lost"? Have you tried doing a search on the drive for *.vdi? It seems more likely that it got accidentally deleted or moved somehow.

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so a problem handeling large files doesn't explain what happened to my 30 Gb file then? it also refused to back-up correctly though, and the hard drive is pre-formatted in NTFS. – Kirstin Dec 17 '10 at 7:45
Bizarre. It does not explain where your file went; as such, don't feel obligated to mark an accepted answer quite yet. Windows Backup doesn't handle large files elegantly just because of how it stores things. It should not cause files to just disappear though. Have you tried searching the drive? – nhinkle♦ Dec 17 '10 at 8:26
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up vote 1 down vote

As designed, the maximum NTFS file size is 16 EB (16 × 10246 bytes) minus 1 KB (1024 bytes)or 18,446,744,073,709,550,592 bytes.

As implemented, the maximum NTFS file size is 16 TB (16 × 10244 bytes) minus 64 KB (64 × 1024 bytes) or 17,592,185,978,880 bytes.

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Nothing personal, but I don't think your answer really contributes much to this question. You're basically just copying verbatim from the Wikipedia article I already linked to. A comment regarding the difference between the designed max file size and implemented max file size might have been relevant, but this answer seems unnecessary. – nhinkle♦ Dec 15 '10 at 9:01
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this does not justify a downvote! (i posted the exact number in bytes) – Thariama Dec 15 '10 at 9:26
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Agreed. While the answer maybe could have been more informative ("They didn't feel the need to implement such a high maximum file size when the current one is still bigger than almost any single drive on the market, let alone when NTFS was first implemented") it provides the exact answer to the question "What's the upper limit on file size?" – Shinrai Dec 15 '10 at 15:35
If this had been the first answer to the question, I would have upvoted it and edited it to add a bit more information. I only downvoted because it was duplicating the existing answer without contributing anything new. – nhinkle♦ Dec 15 '10 at 20:52
I'd like to correct 10246 and 10244 to 1024^6 and 1024^4 or with superscript. Unfortunately I get a msg about edits have to be at least 6 char or something. so stupid system won't let me change it. Was a a bit interesting that there's such a difference between design and implementation EB and TB – barlop Jun 24 '11 at 16:57
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