Date: Wed, 26 Apr 2000 23:05:59 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: "John W. DeBoskey" <jwd@unx.sas.com> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Support for large mfs Message-ID: <200004270605.XAA00807@apollo.backplane.com> References: <200004270554.BAA34693@bb01f39.unx.sas.com>
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:Hi,
:
: Today, we tried to create a 5Gig mfs. It turns out this is
:not such a good idea. It turns out that support is basically
:limited to an int. Extracts from some of the appropriate files
:show some of the problems...
More then just a few.... MFS uses an mmap()'d segment, so you
can't create an MFS partition larger then what a process can mmap()
anyway. The max is going to be around 2-3 GB.
You should be able to create a large virtual VN device. man
vnconfig for more information - you have the choice of making it
file-backed, swap-backed, or swap-backed with the swap pre-reserved.
file-backed VN devices have a sector size of 512 bytes (which is
standard). Swap-backed VN devices have a sector size of a page (4K on
PC's).
vnconfig up a VN device, disklabel it, and newfs away. You can also
turn softupdates on in the VN filesystem partitions. I've tested VN
all the way to a terrabyte - and just managed to newfs it before I ran
out of swap :-)
-Matt
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