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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. |
DX2BK
Cross Reference (Contains links to field and bit definitions)
DX2BK Prolog
NAME : HCPDX2BK
DESCRIPTION: Minidisk extent index level 2.
DSECT : DX2BK
FUNCTION : A DX2BK contains the minidisk extents for a
minidisk-pool.
LOCATED BY : HCPDX1BK - DX1DX2Bk points to the DX2BK.
CREATED BY : HCPAMD44 When a Diagnose 244 is issued by the user.
DELETED BY : HCPAMD44 During an identify pool function the
previous DX1BK will be deleted if any.
HCPMSMDP During storage reset operation.
COMMENTS :
DX2BK Control Block Content
DX2BK DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure DX2BK Minidisk extent index level 2. Each entry in this table represents one minidisk extent. This is the first part of an entry which is split into four parts. This part contains the pool-relative-block number start and end for the extent. 0000 0 Signed 4 DX2PRBNS Pool-Relative-block number (PRBN) start for this minidisk extent. ****************------- 0004 4 Signed 4 DX2PRBNE PRBN end for this minidisk extent. ****************------- 00000008 DX21ENT4 *-DX2PRBNS Used to get length of this entry. ****************------- 0008 8 Dbl-Word 8 DX2PRBNX (127) Next entry in table This is the second part of an entry which is split into four parts. This part contains the device-relative-block number start and end for the extent. 0400 1024 Signed 4 DX2DRBNS Device-Relative-block number (DRBN) start for this minidisk extent. ****************------- 0404 1028 Signed 4 DX2DRBNE DRBN end for this minidisk extent. ****************------- 00000008 DX22ENT4 *-DX2DRBNS Used to get length of this entry. ****************------- 0408 1032 Dbl-Word 8 DX2DRBNX (127) Next entry in table. This is the third part of an entry which is split into four parts. This part contains the minidisk's starting and ending cylinder or block numbers on the physical device. 0800 2048 Signed 4 DX2MEXT (0) Minidisk extent information 0800 2048 Signed 4 DX2MSEXT Minidisk starting cylinder (CKD/ ECKD) or 512-byte block (FBA) 0804 2052 Signed 4 DX2MEEXT Minidisk ending cylinder (CKD/ ECKD) or 512-byte block (FBA) ****************------- 00000008 DX23ENT4 *-DX2MEXT Used to get length of this entry. ****************------- 0808 2056 Dbl-Word 8 DX2MCYNX (127) Next entry in table. This is the fourth part of an entry which is split into four parts. This part contains the EXPBK or MEXBK address, status field and the virtual device number. 0C00 3072 Address 4 DX2EXPBK Address of the EXPBK or MEXBK for these PRBN. ****************------- 0C04 3076 Signed 2 DX2VDEVN Virtual device number for the minidisk. ****************------- 0C06 3078 Bitstring 1 DX2STAT Status byte ****************------- 1... .... DX2INVLD X'80' Indicates this extent is invalid. .1.. .... DX2READO X'40' Indicates that this extent is on a read only DASD. If this extent is mapped the PTE should have the page protect bit set on. ..1. .... DX2FBA X'20' Indicates that this minidisk extent resides on an FBA device 0C07 3079 Bitstring 1 * Reserved for IBM use. ****************------- 00000008 DX24ENT4 *-DX2EXPBK Used to get length of this entry. ****************------- 0C08 3080 Dbl-Word 8 DX2EXPNX (127) Next entry in table. The following equates are used to get the number of entries that will fit in a page. DX2ETBSZ is the total size in bytes of all the parts of an entry. DX2NMENT is the total number of entries that will fit in a page. 00000020 DX2ETBSZ (DX21ENT4+DX22ENT4+DX23ENT4+DX24E NT4) 00000080 DX2NMENT 4096/DX2ETBSZ If the number of entries that can be contained in this control block decreases to 127 or lower then HCPDX1BK will have to increase to two or more contiguous pages. Therefore the following statement will fail when the number of entries decreases to 127 or lower. 1000 4096 Address 4 * (0) IEV075 will res ult if DX2NMENT LE 127 @P3714FM
DX2BK Storage Layout
*** DX2BK - Minidisk extent index level 2. * * +---------------------------+---------------------------+ * 0 | DX2PRBNS | DX2PRBNE | * +---------------------------+---------------------------+ * 8 | | * = DX2PRBNX = * | | * +---------------------------+---------------------------+ * 400 | DX2DRBNS | DX2DRBNE | * +---------------------------+---------------------------+ * 408 | | * = DX2DRBNX = * | | * +---------------------------+---------------------------+ * 800 | DX2MSEXT | DX2MEEXT | * +---------------------------+---------------------------+ * 808 | | * = DX2MCYNX = * | | * +---------------------------+-------------+------+------+ * C00 | DX2EXPBK | DX2VDEVN |:STAT |//////| * +---------------------------+-------------+------+------+ * C08 | | * = DX2EXPNX = * | | * +-------------------------------------------------------+ *1000 * *** DX2BK - Minidisk extent index level 2.
DX2BK Cross Reference
(contains links to field and bit definitions)Symbol Dspl Value -------------- ---- -----DX2DRBNE 0404
DX2DRBNS 0400
DX2DRBNX 0408
DX2ETBSZ 0C08 00000020
DX2EXPBK 0C00
DX2EXPNX 0C08
DX2FBA 0C06 20
DX2INVLD 0C06 80
DX2MCYNX 0808
DX2MEEXT 0804
DX2MEXT 0800
DX2MSEXT 0800
DX2NMENT 0C08 00000080
DX2PRBNE 0004
DX2PRBNS 0000
DX2PRBNX 0008
DX2READO 0C06 40
DX2STAT 0C06
DX2VDEVN 0C04
DX21ENT4 0004 00000008
DX22ENT4 0404 00000008
DX23ENT4 0804 00000008
DX24ENT4 0C07 00000008
Last updated on 3 Aug 1999 at 11:54:07 EDT.
Copyright IBM Corporation, 1990, 1999