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File name limitations when accessing Windows file shares from a Mac

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Mark Wilson

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Earlier this afternoon, one of my friends got in touch with “a quick tech question” (it had to be quick as his method of communication was SMS text message):

“…We have a brand new, state of the art pre-press system which, for some reason, is running Windows 2000. It seems that this OS cannot handle file names longer than 27 chars…”

I was sure that this would be an integration issue rather than an operating system restriction as I’ve never come across any such limitation with a Windows NT-based Windows system (leaving aside the question as to why would a state of the art device use an old and unsupported operating system?) – besides which, I was in no mood to give an office full of professional Mac users an excuse to bash Microsoft!

After a very short time spent googling, I found a newsgroup post which explains the issue. It seems that Apple filing protocol (AFP) 2.2, used by Windows Services for Macintosh, has a 31-character limit (presumably 4 of those characters are used by the driveletter:\ portion of the filename and another one somewhere else leaving 27 visible characters). AFP 3.x has no such limitation but, as all modern Macs can use SMB to communicate natively with Windows servers, there seems little point in using Services for Macintosh these days. Looking at the Wikipedia article on AFP, there may also be restrictions on file sizes with AFP and certain client-server combinations.

Comments

2 responses to “File name limitations when accessing Windows file shares from a Mac”

  1. Alex Coles avatar
    Alex Coles

    “After a very short time spent googling” — I’m sure your friend — whoever he/she is — could have googled for the answer themselves, if they had known what search terms to use.

    I suspect the 27 character filename length is nothing to do with the drive letter, but rather, 27 character filename plus “.ext” equals 31 characters. I’d imagine your friend didn’t realise this because many Mac file formats to not need a file extension.

    Off-topic: I am a very lazy individual and would appreciate it if the comment notification box was ticked by default :)

  2. Mark Wilson avatar
    Mark Wilson

    I’m sure that my friend was just very busy renaming files to get them below the 27 character limit and googling “windows macintosh file name length” or similar was not a priority. After all, when I have Mac problems I call the same friend for advice and I’m only to pleased to reciprocate with Windows issues. I’m glad it was so easy to find an answer ;-) .

    Yep – you’re probably right – .extension would make more sense for the 4 character discrepancy between the apparant limit of 27 characters and the stated limit of 31.

    Off-topic: automatically enabling comment notification would probably be contrary to direct marketing regulations in the UK (I understand that e-mail opt-ins should be deselected by default, although it seems to be far from clear) – more to the point, it might annoy the majority of people who leave comments on this site… I’d rather keep the few visitors that I do have than to turn them off with site-generated spam. Come to think of it though, most of the comments I get are spam!

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