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- From: kjb@calmasd.prime.com (Ken Brucker)
- Newsgroups: comp.os.vms
- Subject: re: REPOST: Parameters for Diskperformance
- Message-ID: <1993Jan12.093635.1108@calmasd.prime.com>
- Date: 12 Jan 93 17:36:35 GMT
- References: <9301111414.AA08411@uu3.psi.com>
- Organization: Computervision, San Diego CA
- Lines: 38
-
- In article <9301111414.AA08411@uu3.psi.com>, leichter@lrw.com (Jerry Leichter) writes:
-
- > The only other consideration in choosing the clustersize is that you should,
- > if possible, choose a clustersize that evenly divides the number of blocks
- > on a track; or failing that, on a cylinder. This ensures that clusters don't
- > cross track (cylinder) boundaries. I don't know the relevant numbers for an
- > RF73, but they'll be in the specs. Make sure you use the number of blocks
- > that will be USED; there will be some spare ones for replacing bad blocks.
-
- Patrick O'Malley gave an interesting presentation at the last DECUS debunking
- the myth of cluster size being a factor of track or cylinder size. With modern
- disk technology the tracks are staggered so the rotational delays involved in
- locating the next piece of a cluster aren't nearly as much as they have been in
- the past. I don't have all the details readily available, but he made a
- believer out of me.
-
- In the long run you will be much better off to make your cluster size
- appropriate to the types of files you have on the disk, as Jerry has already
- discussed.
-
- >
- > You can move the index file from its default position in the center of the
- > disk by using the /INDEX qualifier of INITIALIZE. However, the default is
- > the position that gives the best performance in normal usage; moving it
- > elsewhere is only useful when you are formatting a disk that is intended to
- > contain a really huge file (larger than half the disk),
-
- A good example of this would be a disk that is going to be used exclusively for
- a system page file. We've used this technique on all of our workstations, thus
- giving as a contiguous page file that almost fills the disk.
-
- Ken
-
- --
- -------------------------------------------------------------------------------
- ** Ken Brucker -- VMS/Ultrix Systems Programmer/Mangler -- Computervision
- ** kjb@calmasd.Prime.COM
- ** Practice Random Kindness and Senseless Acts of Beauty
-