What is DKA100:XQPCACHE, Extent cache, etc., from SH DEV D/FU?

From: AEF (spamsink2001_at_yahoo.com)
Date: 07/29/05 

Date: 29 Jul 2005 08:18:33 -0700

Hello cov readers!

There is something below with cache name _xxxxx$DKA100:XQPCACHE. Why is
the system disk name there? All disks on a given system are named this
way. I guess there is only one "XQP cache" for each system. (What
happens to this with disks shared in VMSclusters?)

What is this cache? Where is it? Why is it so large? (There appears to
be no room at all for this in memory.) Why is the "maximum number of
blocks in cache (96734) larger than its own size (64)? Where is it in
the docs (I did look and I could not find it).

And any other words that would clear up what all these caches are.

Note: I'm not trying to address any problem. I just want to know what
this is.

Hardware: MicroVAX 3100
Software: VMS v6.1 VAX (I see the same on my v6.2 systems)

Thanks!

Disk xxxxx$DKA200:, device type RZ28, is online, mounted, file-oriented
device,
    shareable, error logging is enabled.

    Error count 0 Operations completed
5204186
    Owner process "" Owner UIC
[SYSTEM]
    Owner process ID 00000000 Dev Prot
S:RWPL,O:RWPL,G:R,W
    Reference count 3 Default buffer size
    512
    Total blocks 4110480 Sectors per track
     86
    Total cylinders 2988 Tracks per cylinder
     16

    Volume label "DATA1" Relative volume number
      0
    Cluster size 4 Transaction count
      3
    Free blocks 967340 Maximum files allowed
 411048
    Extend quantity 5 Mount count
      1
    Mount status System Cache name
"_xxxxx$DKA100:XQPCACHE"
    Extent cache size 64 Maximum blocks in extent cache
  96734
    File ID cache size 64 Blocks currently in extent
cache 53024
    Quota cache size 0 Maximum buffers in FCP cache
    980
    Volume owner UIC [SYSTEM] Vol Prot
S:RWCD,O:RWCD,G:RWCD,W:RWCD

  Volume status: subject to mount verification, write-back caching
enabled.

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