(start is here)
Exadata Storage Snapshots are based on the
Sparse concept:
Sparse Griddisk => Sparse ASM diskgroup => Snapshot database
- At the bottom level of sparse concept is the sparse griddisk.
- On top of griddisk is created sparse ASM diskgroup,
- On top of sparse ASM diskgroup is created Snapshot Database.
Sparse Griddisk
Sparse griddisk is part of celldisk (as usual), the difference is in virtualsize attribute, which define sparse (logical) size of sparse griddisk:CellCLI> create griddisk all harddisk prefix=SPARSE, size=317.6875G, virtualsize=3176G
size=317.6875G - is the physical (real) size of our SPARSE disk.
Each sparse griddisk has 2 attributes: physical (real) size and virtual size.
Physical size limited by size 4T per one hard disk.
Virtual size is limited by 100T per hard disk (25 times more than real size).
As i understand virtual size define the amount of metadata at the sparse grid disk.
CellCLI> list griddisk detail
name: SPARSE_CD_00_ed03celadm01
asmDiskGroupName: SPARSE
asmDiskName: SPARSE_CD_00_ED03CELADM01
asmFailGroupName: ED03CELADM01
availableTo:
cachedBy: "FD_04_ed03celadm01, FD_07_ed03celadm01, FD_05_ed03celadm01, FD_06_ed03celadm01"
cachingPolicy: default
cellDisk: CD_00_ed03celadm01
comment:
creationTime: 2019-01-24T13:51:40+03:00
diskType: HardDisk
errorCount: 0
id: dfd71cd3-b154-45e4-9a08-b6dcc29ffe65
size: 317.6875G
sparse: TRUE
status: active
virtualSize: 3.1015625T
Sparse ASM diskgroup
Sparse ASM diskgroup is the usual ASM diskgroup. We create it with command:$ sqlplus / as sysasm
SQL> create diskgroup SPARSE
normal redundancy
disk 'o/*/SPARSE_*'
attribute
'compatible.asm' = '18.0.0.0',
'compatible.rdbms' = '12.1.0.2',
'cell.smart_scan_capable' = 'true',
'cell.sparse_dg' = 'allsparse',
'au_size' = '4M';
The only difference is 'cell.sparse_dg'='allsparse' attribute.
You can use any name for this group.
ASMCMD> lsdg
State Type Total_MB Free_MB Req_mir_free_MB Usable_file_MB Voting_files Name
MOUNTED NORMAL 7778304 7531228 216064 3657582 N DATAC1/
MOUNTED NORMAL 894720 889968 29824 430072 Y DBFSC1/
MOUNTED NORMAL 117080064 117078216 3252224 56912996 N SPARSE/
ASMCMD> lsattr -l -G SPARSE
Name Value
access_control.enabled FALSE
access_control.umask 066
appliance._partnering_type EXADATA FIXED
appliance.mode TRUE
ate_conversion_done true
au_size 4194304
cell.smart_scan_capable TRUE
cell.sparse_dg allsparse
compatible.asm 18.0.0.0.0
compatible.rdbms 12.1.0.2.0
content.check FALSE
content.type data
content_hardcheck.enabled FALSE
disk_repair_time 12.0h
failgroup_repair_time 24.0h
idp.boundary auto
idp.type dynamic
logical_sector_size 512
phys_meta_replicated true
preferred_read.enabled FALSE
scrub_async_limit 1
scrub_metadata.enabled TRUE
sector_size 512
thin_provisioned FALSE
vam_migration_done true
ASMCMD> lsattr -l -G DATAC1
Name Value
access_control.enabled TRUE
access_control.umask 066
appliance._partnering_type EXADATA FIXED
appliance.mode TRUE
ate_conversion_done true
au_size 4194304
cell.smart_scan_capable TRUE
cell.sparse_dg allnonsparse
compatible.advm 18.0.0.0.0
compatible.asm 18.0.0.0.0
compatible.rdbms 11.2.0.4.0
content.check FALSE
content.type data
content_hardcheck.enabled FALSE
disk_repair_time 12.0h
failgroup_repair_time 24.0h
idp.boundary auto
idp.type dynamic
logical_sector_size 512
phys_meta_replicated true
preferred_read.enabled FALSE
scrub_async_limit 1
scrub_metadata.enabled TRUE
sector_size 512
thin_provisioned FALSE
vam_migration_done true
In this article we show how to create sparse griddidk and sparse ASM diskgroup.
