ASM虚拟元数据-advm asm file 7

数据库技术加油站 2023-08-23

【作者简介】

本人医疗行业DBA，精通oracle底层；会文件、触发器加密的勒索恢复、asm磁盘组不能mount及各种灾难恢复，后面将利用空闲时间将自己工作中遇到的问题及整理的资料分享给更多愿意学习和提升自己的dba。作者微信号：Oray_123

【正文】

1、ASM ADVM介绍

* 逻辑卷（ADVM）是11gR2引入的一项技术；
* 简单理解advm，就是通过在现有ASM磁盘组上划分卷，再格式化成ACFS文件系统，挂载到文件系统层面进行使用；
* 使用逻辑卷的目的就是为了让ASM磁盘组支持存放更多的文件，比如普通的文件、安装包、安装代码等等；


* 前台有ADVM，那么后台必然有一个位置来进行存放，那么ADVM是存放在asm具体哪里的呢？
* asm file 7号文件是asm存放逻辑卷目录的extent的分配表；通过分配表定位就能够找到具体ADVM存放的内容；


* 一个磁盘组可以创建多个ADVM，ACFS通过ADVM接口构建在ASM磁盘组上运行；
* 要看到ASM ADVM的元数据信息，必须先安装、配置acfs相关服务，以下是具体的实验：

2、定位ADVM

1)通过视图查询


set line 200
col diskgroup_name for a15
col disk_name for a10
col path for a40
select a.GROUP_NUMBER,a.name diskgroup_name,a.type,a.allocation_unit_size/1024/1024 unit_mb,a.voting_files,b.name disk_name,b.path,
b.os_mb/1024 as os_gb,b.total_mb/1024 as total_gb,b.free_mb/1024 as free_gb
 from v$asm_diskgroup a,v$asm_disk b where a.group_number=b.group_number;


select number_kffxp file#, disk_kffxp disk#, count(disk_kffxp) extents
 from x$kffxp
 where group_kffxp=1
 and disk_kffxp <> 65534
 group by number_kffxp, disk_kffxp
 order by 1;
     FILE#  DISK#   EXTENTS
---------- ---------- ----------
   1      0         1
   1      1         1
   2      1         1
   3      0        42
   3      1        43
   4      0         4
   4      1         4
   5      0         1
   6      1         1
   8      0         1
   9      0         1


通过查询，我们可以看到，并没有file#为7的行，说明没有对应的advm元数据信息，这是因为我们默认就没有启用acfs功能；


set line 200 pages 1000
col "disk name" for a20
col path for a30
col type for a20
col au for 99999
SELECT x.number_kffxp file#,x.xnum_kffxp "Extent",case lxn_kffxp
  when 0 then 'Primary Copy'
  when 1 then 'Mirrored Copy'
  when 2 then '2nd Mirrored Copy or metadata'
  else 'Unknown' end type,
x.au_kffxp "AU",
x.disk_kffxp "Disk #",
d.name "Disk name",
d.path,
d.GROUP_NUMBER,
d.DISK_NUMBER
FROM x$kffxp x, v$asm_disk_stat d
WHERE x.group_kffxp=d.group_number
and x.disk_kffxp=d.disk_number
and x.group_kffxp=1
and x.number_kffxp=7
ORDER BY 1, 2;


安装acfs相关服务：
[root@hisdb01 ~]# acfsdriverstate supported
ACFS-9459: ADVM/ACFS is not supported on this OS version: 'centos-release-7-6.1810.2.el7.centos.x86_64
'
ACFS-9201: Not Supported


[root@hisdb01 ~]# acfsroot install
ACFS-9459: ADVM/ACFS is not supported on this OS version: 'centos-release-7-6.1810.2.el7.centos.x86_64
'


[root@hisdb01 ~]# find u01 -name osds_acfslib.pm
/u01/app/11.2.0/grid/lib/osds_acfslib.pm
/u01/app/11.2.0/grid/.patch_storage/28729245_Nov_2_2018_04_47_07/files/lib/osds_acfslib.pm
/u01/app/oracle/product/11.2.0/db_1/lib/osds_acfslib.pm


[root@hisdb01 ~]# vi u01/app/11.2.0/grid/lib/osds_acfslib.pm
  # Testing for "oraclelinux_release", etc prevents us from dropping
  # into the code below from other RH based distros like CentOS, for example.
  if ((defined($release)) &&                     # Redhat or OEL if defined
      (($release =~ /^redhat-release/) ||        # straight RH
       ($release =~ /^enterprise-release/) ||    # Oracle Enterprise Linux
        ($release =~ /^centos-release/) ||    # CentOS hack  --添加这一行
       ($release =~ /^oraclelinux-release/)))    # Oracle Linux


[root@hisdb01 ~]# acfsroot install
ACFS-9300: ADVM/ACFS distribution files found.
ACFS-9307: Installing requested ADVM/ACFS software.
ACFS-9308: Loading installed ADVM/ACFS drivers.
ACFS-9321: Creating udev for ADVM/ACFS.
ACFS-9323: Creating module dependencies - this may take some time.
ACFS-9154: Loading 'oracleoks.ko' driver.
ACFS-9154: Loading 'oracleadvm.ko' driver.
ACFS-9154: Loading 'oracleacfs.ko' driver.
ACFS-9327: Verifying ADVM/ACFS devices.
ACFS-9156: Detecting control device '/dev/asm/.asm_ctl_spec'.
ACFS-9156: Detecting control device '/dev/ofsctl'.
ACFS-9309: ADVM/ACFS installation correctness verified.
启动acfs相关服务：
[root@hisdb01 ~]# acfsload start
ACFS-9391: Checking for existing ADVM/ACFS installation.
ACFS-9392: Validating ADVM/ACFS installation files for operating system.
ACFS-9393: Verifying ASM Administrator setup.
ACFS-9308: Loading installed ADVM/ACFS drivers.
ACFS-9327: Verifying ADVM/ACFS devices.
ACFS-9156: Detecting control device '/dev/asm/.asm_ctl_spec'.
ACFS-9156: Detecting control device '/dev/ofsctl'.
ACFS-9322: completed


[root@hisdb01 ~]# acfsdriverstate version
ACFS-9325:     Driver OS kernel version = 3.10.0-862.el7.x86_64(x86_64).
ACFS-9326:     Driver Oracle version = 181028.


使用acfs：
为advm创建一个单独的磁盘不是必须的，但是建议把数据文件和ACFS文件隔离开，以下是创建磁盘组后，在磁盘组上面再创建的逻辑卷，要求磁盘组的COMPATIBLE.ASM与COMPATIBLE.ADVM必须设置为11.2或以上，同时ADVM/ACFS驱动要被加载(在集群环境中，已经默认加载，而在单实例环境中，需要手动加载)。
sqlplus  as sysasm
create diskgroup ACFS  disk 'ORCL:ASMDISK5', 'ORCL:ASMDISK6'  attribute 'COMPATIBLE.ASM' = '11.2', 'COMPATIBLE.ADVM' = '11.2';
$ asmcmd volcreate -G ACFS -s 2G ACFS_VOL1
$ asmcmd volcreate -G ACFS -s 2G ACFS_VOL2
$ asmcmd volinfo -a


我这里因为磁盘没有添加，选择在现有磁盘组上面创建：
[grid@hisdb01 ~]$ asmcmd lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576     60000    57312                0           57312              0             N  DATA/


[grid@hisdb01 ~]$ asmcmd volcreate -G DATA -s 2G DATA_VOL1
[grid@hisdb01 ~]$ asmcmd volcreate -G DATA -s 2G DATA_VOL2
[grid@hisdb01 ~]$ asmcmd volinfo -a
Diskgroup Name: DATA


   Volume Name: DATA_VOL1
   Volume Device: /dev/asm/data_vol1-467
   State: ENABLED
   Size (MB): 2048
   Resize Unit (MB): 32
   Redundancy: UNPROT
   Stripe Columns: 4
   Stripe Width (K): 128
   Usage: 
   Mountpath: 


   Volume Name: DATA_VOL2
   Volume Device: dev/asm/data_vol2-467
   State: ENABLED
   Size (MB): 2048
   Resize Unit (MB): 32
   Redundancy: UNPROT
   Stripe Columns: 4
   Stripe Width (K): 128
   Usage: 
   Mountpath: 
创建完成后，还没有相应的挂载目录和逻辑卷相关联，我们通过查询发现已经从DATA磁盘组中剥离了4g出来了，如下：
[grid@hisdb01 ~]$ asmcmd lsdg
State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576     60000    53213                0           53213              0             N  DATA/


在逻辑卷上创建ACFS集群文件系统
[root@hisdb01 ~]# mkfs -t acfs dev/asm/data_vol1-467
mkfs.acfs: version                   = 11.2.0.4.0
mkfs.acfs: on-disk version           = 39.0
mkfs.acfs: volume                    = /dev/asm/data_vol1-467
mkfs.acfs: volume size               = 2147483648
mkfs.acfs: Format complete.
[root@hisdb01 ~]# mkdir acfs1
[root@hisdb01 ~]# chown -R oracle:oinstall acfs1
[root@hisdb01 ~]# mount -t acfs dev/asm/data_vol1-467 acfs1
[root@hisdb01 ~]# df -Th
Filesystem              Type      Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs        92G   29G   64G  32% /
...
/dev/asm/data_vol1-467  acfs      2.0G   43M  2.0G   3% /acfs1


[grid@hisdb01 ~]$ asmcmd volinfo -G DATA DATA_VOL1
Diskgroup Name: DATA


   Volume Name: DATA_VOL1
   Volume Device: dev/asm/data_vol1-467
   State: ENABLED
   Size (MB): 2048
   Resize Unit (MB): 32
   Redundancy: UNPROT
   Stripe Columns: 4
   Stripe Width (K): 128
   Usage: ACFS
   Mountpath: /acfs1 


[root@hisdb01 acfs1]# cp /software/p13390677_112040_Linux-x86-64_1of7.zip .
[root@hisdb01 acfs1]# ll
total 1364544
drwx------ 2 root root      65536 Jul 20 16:14 lost+found
-rw-r--r-- 1 root root 1395582860 Jul 20 16:36 p13390677_112040_Linux-x86-64_1of7.zip    --可以看到普通的文件就能存放到这里面了；
[root@hisdb01 acfs1]# pwd
/acfs1




select number_kffxp file#, disk_kffxp disk#, count(disk_kffxp) extents
 from x$kffxp
 where group_kffxp=1
 and disk_kffxp <> 65534
 group by number_kffxp, disk_kffxp
  6   order by 1;


     FILE#  DISK#   EXTENTS
---------- ---------- ----------
   1      0         1
   1      1         1
   2      1         1
   3      0        42
   3      1        43
   4      0         4
   4      1         4
   5      0         1
   6      1         1
   7      0         1  --再次查看，确实有file# 7的信息了；


set line 200 pages 1000
col "disk name" for a20
col path for a30
col type for a20
col au for 99999
SELECT x.number_kffxp file#,x.xnum_kffxp "Extent",case lxn_kffxp
  when 0 then 'Primary Copy'
  when 1 then 'Mirrored Copy'
  when 2 then '2nd Mirrored Copy or metadata'
  else 'Unknown' end type,
x.au_kffxp "AU",
x.disk_kffxp "Disk #",
d.name "Disk name",
d.path,
d.GROUP_NUMBER,
d.DISK_NUMBER
FROM x$kffxp x, v$asm_disk_stat d
WHERE x.group_kffxp=d.group_number
and x.disk_kffxp=d.disk_number
and x.group_kffxp=1
and x.number_kffxp=7
ORDER BY 1, 2;

3、kfed 解析ADVM

3、kfed 解析ADVM
set line 200
col diskgroup_name for a15
col disk_name for a10
col path for a40
select a.group_number,a.name diskgroup_name,a.type,a.allocation_unit_size/1024/1024 unit_mb,a.voting_files,b.name disk_name,b.path,
b.os_mb/1024 as os_gb,b.total_mb/1024 as total_gb,b.free_mb/1024 as free_gb
  3  from v$asm_diskgroup a,v$asm_disk b where a.group_number=b.group_number;


GROUP_NUMBER DISKGROUP_NAME  TYPE         UNIT_MB VO DISK_NAME  PATH            OS_GB   TOTAL_GB    FREE_GB
------------ --------------- -------------------- ---------- -- ---------- ---------------------------------------- ---------- ---------- ----------
     1 DATA       EXTERN         1 N  DATA_0000  /dev/asmdisk4           29.296875  29.296875 25.9814453
     1 DATA       EXTERN         1 N  DATA_0001  /dev/asmdisk5           29.296875  29.296875  25.984375
     2 FRA       EXTERN         1 N  FRA_0000   /dev/asmdisk6            9.765625   9.765625 8.41015625
--先读取文件目录，是在10号au上
[grid@hisdb01 ~]$ kfed read /dev/asmdisk4 aun=0 blkn=0|egrep -i "aus|f1b1locn"
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.f1b1locn:                      2 ; 0x0d4: 0x00000002


[grid@hisdb01 ~]$ kfed read /dev/asmdisk4 aun=2 blkn=7 aus=1M|egrep "block|disk|au"|egrep -v "65535|4294967295"
kfbh.block.blk:                       7 ; 0x004: blk=7
kfbh.block.obj:                       1 ; 0x008: file=1
kfffde[0].xptr.au:                 1345 ; 0x4a0: 0x00000541  --分配信息在0号磁盘的1345AU上，和上面视图查询结果完全一致
kfffde[0].xptr.disk:                  0 ; 0x4a4: 0x0000


--block 0.它只包含了ADVM逻辑卷的标记(++AVD_DG_NUMBER)
[grid@hisdb01 ~]$ kfed read /dev/asmdisk4 aun=1345 aus=1M blkn=0|more
kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                           22 ; 0x002: KFBTYP_VOLUMEDIR
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:                       7 ; 0x008: file=7
kfbh.check:                  1556606794 ; 0x00c: 0x5cc7ef4a
kfbh.fcn.base:                     4666 ; 0x010: 0x0000123a
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kffdnd.bnode.incarn:                  1 ; 0x000: A=1 NUMM=0x0
kffdnd.bnode.frlist.number:  4294967295 ; 0x004: 0xffffffff
kffdnd.bnode.frlist.incarn:           0 ; 0x008: A=0 NUMM=0x0
kffdnd.overfl.number:                 1 ; 0x00c: 0x00000001
kffdnd.overfl.incarn:                 1 ; 0x010: A=1 NUMM=0x0
kffdnd.parent.number:                 0 ; 0x014: 0x00000000
kffdnd.parent.incarn:                 1 ; 0x018: A=1 NUMM=0x0
kffdnd.fstblk.number:                 0 ; 0x01c: 0x00000000
kffdnd.fstblk.incarn:                 1 ; 0x020: A=1 NUMM=0x0
kfvvde.entry.incarn:                  1 ; 0x024: A=1 NUMM=0x0
kfvvde.entry.hash:                    0 ; 0x028: 0x00000000
kfvvde.entry.refer.number:   4294967295 ; 0x02c: 0xffffffff
kfvvde.entry.refer.incarn:            0 ; 0x030: A=0 NUMM=0x0
kfvvde.volnm:           ++AVD_DG_NUMBER ; 0x034: length=15
kfvvde.usage:                           ; 0x054: length=0
kfvvde.dgname:                          ; 0x074: length=0
kfvvde.clname:                          ; 0x094: length=0
kfvvde.mountpath:                       ; 0x0b4: length=0
kfvvde.drlinit:                       0 ; 0x4b5: 0x00
kfvvde.pad1:                          0 ; 0x4b6: 0x0000
kfvvde.volfnum.number:                0 ; 0x4b8: 0x00000000
kfvvde.volfnum.incarn:                0 ; 0x4bc: 0x00000000
kfvvde.drlfnum.number:                0 ; 0x4c0: 0x00000000
kfvvde.drlfnum.incarn:                0 ; 0x4c4: 0x00000000
kfvvde.volnum:                        0 ; 0x4c8: 0x0000
kfvvde.avddgnum:                    467 ; 0x4ca: 0x01d3
kfvvde.extentsz:                      0 ; 0x4cc: 0x00000000
kfvvde.volstate:                      4 ; 0x4d0: D=0 C=0 R=1
kfvvde.pad[0]:                        0 ; 0x4d1: 0x00
...
--block 1，而真正的逻辑卷的信息其实位于block 1及以后：
[grid@hisdb01 ~]$ kfed read /dev/asmdisk4 aun=1345 aus=1M blkn=1|more
kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                           22 ; 0x002: KFBTYP_VOLUMEDIR
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       1 ; 0x004: blk=1
kfbh.block.obj:                       7 ; 0x008: file=7
kfbh.check:                  2199406070 ; 0x00c: 0x831845f6
kfbh.fcn.base:                     4954 ; 0x010: 0x0000135a
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kffdnd.bnode.incarn:                  1 ; 0x000: A=1 NUMM=0x0
kffdnd.bnode.frlist.number:  4294967295 ; 0x004: 0xffffffff
kffdnd.bnode.frlist.incarn:           0 ; 0x008: A=0 NUMM=0x0
kffdnd.overfl.number:                 2 ; 0x00c: 0x00000002  --表示指向同层级的下一个块
kffdnd.overfl.incarn:                 1 ; 0x010: A=1 NUMM=0x0
kffdnd.parent.number:        4294967295 ; 0x014: 0xffffffff
kffdnd.parent.incarn:                 0 ; 0x018: A=0 NUMM=0x0
kffdnd.fstblk.number:                 0 ; 0x01c: 0x00000000  --表示指向上一层的块
kffdnd.fstblk.incarn:                 1 ; 0x020: A=1 NUMM=0x0
kfvvde.entry.incarn:                  1 ; 0x024: A=1 NUMM=0x0  --kfvvde这部分信息是acfs元数据内容
kfvvde.entry.hash:                    0 ; 0x028: 0x00000000
kfvvde.entry.refer.number:   4294967295 ; 0x02c: 0xffffffff
kfvvde.entry.refer.incarn:            0 ; 0x030: A=0 NUMM=0x0
kfvvde.volnm:                 DATA_VOL1 ; 0x034: length=9    --asm advm卷名称
kfvvde.usage:                      ACFS ; 0x054: length=4    --advm的type类型，这里使用的是acfs
kfvvde.dgname:                          ; 0x074: length=0
kfvvde.clname:                          ; 0x094: length=0
kfvvde.mountpath:                /acfs1 ; 0x0b4: length=6    --挂载点
kfvvde.drlinit:                       0 ; 0x4b5: 0x00
kfvvde.pad1:                          0 ; 0x4b6: 0x0000
kfvvde.volfnum.number:              273 ; 0x4b8: 0x00000111  --逻辑卷文件，表示volume file number
kfvvde.volfnum.incarn:       1142697595 ; 0x4bc: 0x441c2e7b
kfvvde.drlfnum.number:                0 ; 0x4c0: 0x00000000  --DRL脏数据记录区域文件，表示volume dirty region logging
kfvvde.drlfnum.incarn:                0 ; 0x4c4: 0x00000000
kfvvde.volnum:                        1 ; 0x4c8: 0x0001    --表示对应的卷组number,从1开始
kfvvde.avddgnum:                    467 ; 0x4ca: 0x01d3
kfvvde.extentsz:                      8 ; 0x4cc: 0x00000008  --这里表示extent大小
kfvvde.volstate:                      2 ; 0x4d0: D=0 C=1 R=0  --这里表示advm卷组状态，2表示可用
...
--block 2
[grid@hisdb01 ~]$ kfed read /dev/asmdisk4 aun=1345 aus=1M blkn=2|more
kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                           22 ; 0x002: KFBTYP_VOLUMEDIR
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       2 ; 0x004: blk=2
kfbh.block.obj:                       7 ; 0x008: file=7
kfbh.check:                  1237494243 ; 0x00c: 0x49c2a9e3
kfbh.fcn.base:                     4946 ; 0x010: 0x00001352
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kffdnd.bnode.incarn:                  1 ; 0x000: A=1 NUMM=0x0
kffdnd.bnode.frlist.number:  4294967295 ; 0x004: 0xffffffff
kffdnd.bnode.frlist.incarn:           0 ; 0x008: A=0 NUMM=0x0
kffdnd.overfl.number:        4294967295 ; 0x00c: 0xffffffff
kffdnd.overfl.incarn:                 0 ; 0x010: A=0 NUMM=0x0
kffdnd.parent.number:        4294967295 ; 0x014: 0xffffffff
kffdnd.parent.incarn:                 0 ; 0x018: A=0 NUMM=0x0
kffdnd.fstblk.number:                 0 ; 0x01c: 0x00000000
kffdnd.fstblk.incarn:                 1 ; 0x020: A=1 NUMM=0x0
kfvvde.entry.incarn:                  1 ; 0x024: A=1 NUMM=0x0
kfvvde.entry.hash:                    0 ; 0x028: 0x00000000
kfvvde.entry.refer.number:   4294967295 ; 0x02c: 0xffffffff
kfvvde.entry.refer.incarn:            0 ; 0x030: A=0 NUMM=0x0
kfvvde.volnm:                 DATA_VOL2 ; 0x034: length=9
kfvvde.usage:                           ; 0x054: length=0
kfvvde.dgname:                          ; 0x074: length=0
kfvvde.clname:                          ; 0x094: length=0
kfvvde.mountpath:                       ; 0x0b4: length=0
kfvvde.drlinit:                       0 ; 0x4b5: 0x00
kfvvde.pad1:                          0 ; 0x4b6: 0x0000
kfvvde.volfnum.number:              274 ; 0x4b8: 0x00000112  --逻辑卷文件
kfvvde.volfnum.incarn:       1142697607 ; 0x4bc: 0x441c2e87
kfvvde.drlfnum.number:                0 ; 0x4c0: 0x00000000  --DRL脏数据记录区域文件
kfvvde.drlfnum.incarn:                0 ; 0x4c4: 0x00000000
kfvvde.volnum:                        2 ; 0x4c8: 0x0002
kfvvde.avddgnum:                    467 ; 0x4ca: 0x01d3
kfvvde.extentsz:                      8 ; 0x4cc: 0x00000008
kfvvde.volstate:                      2 ; 0x4d0: D=0 C=1 R=0
...


由于我创建了两个ACFS，从1号块开始每个block对应一个acfs，第2个块对应对2个acfs..
所以 asm file 7 block 1 包含的是第一个逻辑卷的信息(kfvvde.volnm:  DATA_VOL1),并且有两个文件关联到这个逻辑卷：
DRL脏数据记录区域文件(kfvvde.drlfnum.number 0)
逻辑卷文件 (kfvvde.volfnum.number:  273)
这些都是特殊文件，所以不会显示在asmcmd ls和v$asm_alias视图中，但是可以通过查询v$asm_file中找到他们：
col type for a10
select file_number "file#",bytes/1024/1024 mb,type from v$asm_file where group_number=1;
     file#     MB TYPE
---------- ---------- ---------------
...
       273   2048 ASMVOL
       274   2048 ASMVOL

4、ADVM总结

一个磁盘组中可以配置一个或多个ASM动态逻辑卷设备。ASM集群文件系统通过ADVM接口构建于ASM磁盘组之上。ADVM跟数据库一样，也是ASM的一个客户端。
有两种与ADVM逻辑卷相关的文件类型：
●  ASMVOL:逻辑卷文件，作为逻辑卷存储设备的容器
●  ASMVDRL:包含脏数据记录区域信息的文件。恢复镜像数据时会用到此文件。

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ASM虚拟元数据-advm asm file 7

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