Re: safe file systems

Mark H. Wood (mwood@mhw.OIT.IUPUI.EDU)
Tue, 30 Sep 1997 11:56:05 -0500 (EST)

On Fri, 26 Sep 1997, Harald Milz wrote:

> Steven N. Hirsch ( wrote:
> >
> > At work we use JFS on IBM RS/6k boxes and Advfs on Digital Unix. AFAIK,
> > they are highly tolerant of the abuse you describe.
> Not necessarily. Open files are truncated to zero length on power loss or
> RESET. Only the meta data is handled in a transaction oriented manner to
> make sure the filesystem is consistent.

If you want to make sure you lose nothing, you need to write a serial
transaction stream to tape and not commit a transaction until this I/O
completes, like the banks do. But now we're getting a bit above the file
system level. Maybe you are asking too much of the file system; maybe
instead you need to overlay it with a transaction monitor.

Mark H. Wood, Lead System Programmer MWOOD@INDYVAX.IUPUI.EDU
Those who will not learn from history are doomed to reimplement it.