Re: huge filesystems

From: Miklos Szeredi
Date: Wed Mar 09 2005 - 17:14:48 EST

> The group I work in has been experimenting with GFS and Lustre, and I did
> some NBD/ENBD experimentation on my own, described at
> My question is, what is the current status of huge filesystems - IE,
> filesystems that exceed 2 terabytes, and hopefully also exceeding 16
> terabytes?
> Am I correct in assuming that the usual linux buffer cache only goes to 16
> terabytes?

The page cache limit is PAGE_CACHE_BITS + BITS_PER_LONG - 1. On i386
that's 12 + 32 - 1 = 43 bits or 8Tbytes. On 64 bit architectures the
size of off_t is the only limit.

> Does the FUSE API (or similar) happen to allow surpassing either the 2T or
> 16T limits?

The API certainly doesn't have any limits. The page cache limit holds
for FUSE too, though with the direct-io mount option the page cache is
not used, so the limit could be removed as well. I'll fix that.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at