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Programming Interface Information:
This information is NOT
intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only. |
MDISK
Cross Reference (Contains links to field and bit definitions)
MDISK Prolog
Name : Minidisk Control Block
Description: Mini-disk Control Block
DSECT : MDISK
Function : This control block maps a defined minidisk for
a virtual machine.
Located by : VDEVMDSK - Mini-disk block for Reserve/Release
Created by : HCPVDSLK
Deleted by : HCPDTDEV, HCPVRILF, HCPVRIRL
MDISK Control Block Content
MDISK DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure MDISK Mini-disk Control Block ** FIELDS FOR ATTACH / DETACH 0000 0 Signed 4 MDINEXT NEXT MDISK ON THIS REAL DEVICE 0004 4 Signed 4 MDILINKS NUMBER OF LINKS TO THIS EXTENT ** FIELDS FOR RELEASE PROCESSING 0008 8 Dbl-Word 8 MDISIOQS (0) NORMAL START REQUEST QUEUES 0008 8 Signed 4 MDIDEOWD ANCHOR FOR QUEUE OF UNSOLICITED IORBKS OWED TO DEVICES 000C 12 Signed 4 MDIDEPND ANCHOR FOR QUEUE OF PENDING UNSOLICITED IORBKS 0010 16 Address 4 MDIRTRQ ADDRESS OF TIMER REQUEST BLOCK 0014 20 Address 4 * RESERVED FOR FUTURE IBM USE 0018 24 Dbl-Word 8 MDIDIAQS (0) DIAGNOSE I/O QUEUES 0018 24 Address 4 MDIQWAIT ANCHOR FOR QUEUE OF IORBKS WAITING FOR RELEASE TO RETRY DIAGNOSE I/O 001C 28 Address 4 * RESERVED FOR FUTURE IBM USE ** LOCKS FOR ACCESS TO THE MINIDISK EXTENT 0020 32 Dbl-Word 8 MDILLOCK (0) LOGICAL LOCK --- DEVICE RESERVED 0020 32 Signed 4 MDIRSVD (0) VDEVBK HOLDING DEVICE RESERVED 0020 32 Address 4 MDIRVDEV ADDRESS OF VDEV RESERVING MINI-DISK (BASE VDEV IF MULTIPLE EXPOSURE DEVICE) 0024 36 Bitstring 1 MDISTAT STATUS FLAGS 1... .... MDIRESVD X'80' INDICATES ACTIVE RESERVE .1.. .... MDIRRSVP X'40' REAL RESERVE IS PENDING ..1. .... MDIRELPD X'20' REAL RELEASE IS PENDING ...1 .... MDIWRKAL X'10' Virtual working allegiance is to be simulated MIDWRKAL interacts with MDIRESVD and MDIRVDEV like this : Case I: MDIRESVD = OFF and MDIWRKAL = ON Working allegiance is active and If MDIRVDEV = 0 Then The minidisk is available. Else MDIRVDEV = the owning vdev address Case II: MDIRESVD = ON and MDIWRKAL = OFF The device is currently reserved MDIRVDEV = the owning vdev address MDIRVDEV cannot be zero Case III: MDIRESVD = ON and MDIWRKAL = ON The device is currently reserved MDIRVDEV = the owning vdev address Working allegiance may or may not be active. If the channel program ended without a Release CCW issued, then working allegiance is over but the device is still unavailable. 0025 37 Bitstring 1 MDILPUM MASK FOR LOGICAL PATH ON WHICH RESERVE WAS MADE 0026 38 Bitstring 1 MDIMDCFL Flag byte for minidisk caching 1... .... MDITHUD X'80' MDC purge on backend is required .1.. .... MDIOVLAP X'40' Mini-disk overlapped - purge cache ..11 .... MDIMDCA X'30' MDC authorization bits used only when setting MDIHSHID ...1 .... MDIMDCD X'10' MDC default authorization MDC will be prohibited ("SET MDC MDISK ON" disabled) if: - minidisk includes CP-system cylinders. CP's I/O to PAGE, SPOL, and DRCT space will clash with any user I/O that is cached. .... 1... MDIMDCP X'08' MDC prohibited for this mdisk .... .1.. MDIRECAC X'04' Do record caching for this mdisk 0027 39 Bitstring 1 MDISMFLG miscellaneous MDISK flags 1... .... MDISMFPO X'80' The minidisk has a full pack overlay link to it .1.. .... MDIEXCLU X'40' Exclusive link held on minidisk ..1. .... MDIDVFP X'20' Minidisk created using DEVNO option ...1 .... MDIQDSK X'10' Minidisk is a Vdisk .... 1... MDIQDSKP X'08' Minidisk is a PRIVATE Vdisk 0028 40 Dbl-Word 8 MDILOCK (0) LOCKWORD FOR RESERVE/RELEASE STATUS 0028 40 Dbl-Word 8 MDIPLOCK (3) PHYSICAL LOCK --- EXTENT IN USE 0040 64 Dbl-Word 8 MDIQLOCK (3) LOCKWORD FOR QUEUE MANIPULATION MDISK extent in cylinders (if CKD or ECKD) or blocks (if FBA) These values are unique for this real device; no other MDISK block represents this exact extent, although other MDISK block extents may overlap this extent. Warning: some CKD/ECKD-only routines cannot handle cylinder numbers larger than 65535; FBA routines can handle 2**32-1. 0058 88 Dbl-Word 8 MDIVEXTN (0) Virtual DASD cylinder/block extents 0058 88 Signed 4 MDIVSEXT Virtual DASD start cylinder/block 005C 92 Signed 4 MDIVEEXT Virtual DASD end cylinder/block All MDISK blocks representing existing virtual dasds (whether "minidisks" or "tdisks" but not "dedicated dasds") are chained in no particular order from the RDEV block. The virtual dasd VDEV blocks in use on this extent are doubly-chained from this MDISK block in descending "link access mode" order. The first VDEV's backward pointer points to the end of the chain. 0060 96 Signed 4 MDIVLINK Pointer to next linked VDEV Counts representing the sum of all VDEVs chained from this MDISK having the specified "link access mode." See also MDIEXCLU bit in MDISMFPO byte. MDILINKS = MDIRDCNT + MDIWRCNT. A stable-read link would be counted once in each of MDIRDCNT and MDISTCNT. These counts summarize the thousands of VDEVs that could be chained from this MDISK block. 0064 100 Signed 4 MDIRDCNT Read link count for minidisk 0068 104 Signed 4 MDIWTCNT Write link count to minidisk 006C 108 Signed 4 MDISTCNT Stable link count for minidisk The minidisk owner is either the user who has the MDISK statement in the directory or the user who created this extent (not using the directory). 0070 112 Character 8 MDIOUSER Mini-disk owner userid 0078 120 Signed 2 MDIOVDEV Mini-disk owner VDEV number MDIHSHID may contain one of the following values: Zero - This minidisk isn't eligible for MDC caching RDEVHSID - when positive, the minidisk is eligible for MDC caching and this field is used to create the MDC hash key. When negative (bit 0 is on), MDC caching is not permitted for this minidisk. X'FFFF' - this minidisk is an FBA device and is not page aligned and is not eligible for MDC caching. Note that if MDIHSHID is positve, caching is allowed provided that it permitted at the system level. 007A 122 Signed 2 MDIHSHID MDC Hash ID MDISK blocks representing tdisks are chained in extent-order from the CPVOLume extent EXTBK within which they reside. This mechanism is used to distinguish free tdisk space from tdisk space in use. 007C 124 Signed 4 MDITNEXT Ptr to next MDISK on EXTBK chain 0080 128 Signed 4 MDIEXTBK Ptr to parent EXTBK MDISK blocks representing Vdisks use the following field to chain in the Qdisk block. 0084 132 Address 4 MDIQDISK Address of QDISK block for Vdisk Miscellanea 0088 136 Signed 4 MDICYLMP Minidisk cache cylinder map. If high order bit on, points to address of cyl map indicating the format of each cylinder. If off, then so far entire mdisk is std and this field contains the DPSBK address for that size. Updated with Compare and Swap. 00000012 MDISIZE ((*-MDISK+7)/8) SIZE IN DWS FOR FREE/FRET
MDISK Storage Layout
*** MDISK - Mini-disk Control Block * * +---------------------------+---------------------------+ * 0 | MDINEXT | MDILINKS | * +---------------------------+---------------------------+ * 8 | MDIDEOWD | MDIDEPND | * +---------------------------+---------------------------+ * 10 | MDIRTRQ |///////////////////////////| * +---------------------------+---------------------------+ * 18 | MDIQWAIT |///////////////////////////| * +---------------------------+------+------+------+------+ * 20 | MDIRVDEV |:STAT |:LPUM |:MDCFL|:SMFLG| * +---------------------------+------+------+------+------+ * 28 | | * = MDIPLOCK = * | | * +-------------------------------------------------------+ * 40 | | * = MDIQLOCK = * | | * +---------------------------+---------------------------+ * 58 | MDIVSEXT | MDIVEEXT | * +---------------------------+---------------------------+ * 60 | MDIVLINK | MDIRDCNT | * +---------------------------+---------------------------+ * 68 | MDIWTCNT | MDISTCNT | * +---------------------------+---------------------------+ * 70 | MDIOUSER | * +-------------+-------------+---------------------------+ * 78 | MDIOVDEV | MDIHSHID | MDITNEXT | * +-------------+-------------+---------------------------+ * 80 | MDIEXTBK | MDIQDISK | * +---------------------------+---------------------------+ * 88 | MDICYLMP | 8C * +---------------------------+ * *** MDISK - Mini-disk Control Block
MDISK Cross Reference
(contains links to field and bit definitions)Symbol Dspl Value -------------- ---- -----MDICYLMP 0088
MDIDEOWD 0008
MDIDEPND 000C
MDIDIAQS 0018
MDIDVFP 0027 20
MDIEXCLU 0027 40
MDIEXTBK 0080
MDIHSHID 007A
MDILINKS 0004
MDILLOCK 0020
MDILOCK 0028
MDILPUM 0025
MDIMDCA 0026 30
MDIMDCD 0026 10
MDIMDCFL 0026
MDIMDCP 0026 08
MDINEXT 0000
MDIOUSER 0070
MDIOVDEV 0078
MDIOVLAP 0026 40
MDIPLOCK 0028
MDIQDISK 0084
MDIQDSK 0027 10
MDIQDSKP 0027 08
MDIQLOCK 0040
MDIQWAIT 0018
MDIRDCNT 0064
MDIRECAC 0026 04
MDIRELPD 0024 20
MDIRESVD 0024 80
MDIRRSVP 0024 40
MDIRSVD 0020
MDIRTRQ 0010
MDIRVDEV 0020
MDISIOQS 0008
MDISIZE 0088 00000012
MDISMFLG 0027
MDISMFPO 0027 80
MDISTAT 0024
MDISTCNT 006C
MDITHUD 0026 80
MDITNEXT 007C
MDIVEEXT 005C
MDIVEXTN 0058
MDIVLINK 0060
MDIVSEXT 0058
MDIWRKAL 0024 10
MDIWTCNT 0068
Last updated on 3 Aug 1999 at 12:13:58 EDT.
Copyright IBM Corporation, 1990, 1999