Re: Limit of 256 NFS Mounted Filesystems

Richard Kaszeta (
Fri, 4 Dec 1998 10:07:55 -0600 (CST)

Michel LESPINASSE writes ("Re: Limit of 64 Mounted Filesystems"):
>I also had this problem because I am mounting a lot of clearcase views at
>my job - I can hardly work with less than 30 mounted filesystems, and the
>64 limit is easy to reach.
>You can change your NR_SUPER in include/linux/fs.h .... I upped it to 256
>and am running without problems with a 2.0.36 kernel

Unfortunately, I've discovered that 256 is as high as one can reasonly
put this limit, even with the 2.1.x kernel, as each nfs (or other
'nodev' type of mount) requires a device of major number 0 and a
different minor number, so there can only be 255 nodev filesystems at
any given time.

Thus, my automounter map with more than 1000 entries for user home
directories will break the linux machines which I am attempting to use
a web servers and samba servers, because in practice they have been
hitting this 256 limit rather frequently. I certainly couldn't use
linux for my mail server.

Anyone have ideas for workarounds? I have a *huge* amount of storage
here for each user, which is why I starting using autofs to start
with---it was the only efficient way of serving home directories
(which are spread over a couple dozen servers and devices anyways, so
most alternative schemes still would run into some of these limits).

IMHO, this is a serious limitation, since for my environment (and for
quite a few other locations I know of with many users) this means my
plans of replacing some of my solaris boxes with linux boxes.

We need to fix this if we are to claim that linux is a serious
candidate for server use.

Richard W Kaszeta 			Graduate Student/Sysadmin				University of MN, ME Dept

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