... ``device.''¹

While NFS does not use the network as a persistent storage medium, it uses it to communicate to servers that, in turn, store the files on local disks.

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... machines.²

For example our department uses the Amd automounter and has seen more than once the severe effects of its aborting. Shells hang because of attempts to access auto-mounted paths in users' $PATH variables, so no new programs can be started. Long-running programs such as emacs also hang because they often perform file systems access for user files, auto-saves, auto-loading emacs-lisp files, etc. Within a few minutes of Amd's abnormal exit, the machine becomes unusable and needs a reboot.

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... interface³

When I speak of the ``vnode interface,'' it should be taken to include the vnode interface that provides operations on files and the VFS interface that provides operations on file systems.

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... ``chain''⁴

Actually a DAG, to provide fan-in and fan-out.

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... ``prepare''⁵

In transaction terminology, ``prepare'' means to stop processing and prepare to either commit or abort.

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... Skinner⁶

Both currently working at Sun Microsystems.

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... Wrapfs.⁷

I do not change system call interface functions such as create(2); the kernel is responsible for calling a particular file systems' vnode operations, and those I may modify.

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... portability.⁸

Most kernels (as well as Amd) were written in C, and cannot handle module linkage of objects that are written in C++. There are more C compilers available than C++ compilers, and C compilers generally produce faster and smaller object modules.

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... backups.⁹

This is what's called ``security by obscurity.''

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... unintentionally.¹⁰

At least once, we all have intended to type rm *.o, but instead typed rm * .o.

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