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Date: Wed, 4 Oct 2006 10:56:56 -0600 From: Andreas Dilger <adilger@...sterfs.com> To: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, xfs@....sgi.com Subject: Directories > 2GB For ext4 we are exploring the possibility of directories being larger than 2GB in size. For ext3/ext4 the 2GB limit is about 50M files, and the 2-level htree limit is about 25M files (this is a kernel code and not disk format limit). Amusingly (or not) some users of very large filesystems hit this limit with their HPC batch jobs because they have 10,000 or 128,000 processes creating files in a directory on an hourly basis (job restart files, data dumps for visualization, etc) and it is not always easy to change the apps. My question (esp. for XFS folks) is if anyone has looked at this problem before, and what kind of problems they might have hit in userspace and in the kernel due to "large" directory sizes (i.e. > 2GB). It appears at first glance that 64-bit systems will do OK because off_t is a long (for telldir output), but that 32-bit systems would need to use O_LARGEFILE when opening the file in order to be able to read the full directory contents. It might also be possible to return -EFBIG only in the case that telldir is used beyond 2GB (the LFS spec doesn't really talk about large directories at all). Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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