Netbooted bands run slower?

[Reti@STONY-BROOK.SCRC.Symbolics.COM (Kalman Reti)]

    Date: Tue, 15 May 90 00:46:53 EDT
    From: barmar@Think.COM

    One of my users mentioned to me that he never uses netboot because he
    noticed that they run slower than locally-booted bands.  He says that he's
    noticed a 10% slowdown from running a netbooted band compared to the
    identical band loaded from a local disk.  Has anyone else noticed this?
    I'm at a loss to explain why this should be.  The best guess I have is that
    the world load files tend to have better disk locality than the paging
    files, so when the band is copied into the paging files there's more disk
    arm motion required.  But I'm not sure why paging files should be
    significantly more fragmented on the disk than world load files.  Most of
    our disks were originally formatted at least 2.5 years ago, and have gone
    through several Genera releases, so the FEP file systems are likely to be
    reasonably fragmented.

						    barmar
In fact, from a fragmenting perspective things should be the other way around.
It is possible to create an incredibly fragmented world file (just copy a band
while slowly writing another file on the same FEP unit, each will get alternating
8 block chunks of the disk), but all the standard methods for creating paging
files that I can think of allocate the blocks at once, thereby getting the best
non-fragmentation that the current state of the disk has to offer.

I'd look at your user's paging files by running SI:PRINT-FEP-FILESYSTEM to see
if they actually are badly fragmented.  Within Symbolics lots of people routinely
run netbooted worlds and no one has reported a similar performance loss.