Oracle ASM的AU(Allocation units)分配

SQL> select group_number,name,sector_size,block_size,allocation_unit_size from v$asm_diskgroup;

GROUP_NUMBER NAME?? SECTOR_SIZE BLOCK_SIZE ALLOCATION_UNIT_SIZE

------------ ------ ----------- ---------- --------------------

1 ARCHDG???????? 512?????? 4096????????????? 1048576

2 DATADG???????? 512?????? 4096????????????? 1048576在Oracle Database 11g中，可以通過類似如下語句在創(chuàng)建磁盤組時指定au_size:

SQL> CREATE DISKGROUP DATA DISK '/dev/raw/raw15', '/dev/raw/raw16',

'/dev/raw/raw17' ATTRIBUTE 'au_size' = '16M', 'compatible.asm' = '11.1' 'compatible.rdbms' = '11.1';ASM允許的相關(guān)參數(shù)可以從DB的實例中查詢獲得，以下是一系列和asm相關(guān)的初始化參數(shù)：

SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ

2??? FROM SYS.x$ksppi x, SYS.x$ksppcv y

3?? WHERE x.indx = y.indx AND x.ksppinm LIKE '%&par%';

Enter value for par: asm

old?? 3:? WHERE x.indx = y.indx AND x.ksppinm LIKE '%&par%'

new?? 3:? WHERE x.indx = y.indx AND x.ksppinm LIKE '%asm%'

NAME?????????????????????????? VALUE??????????????? DESCRIB

------------------------------ -------------------- ------------------------------------------------------------

asm_diskstring????????????????????????????????????? disk set locations for discovery

_asm_disk_repair_time????????? 14400??????????????? seconds to wait before dropping a failing disk

asm_diskgroups????????????????????????????????????? disk groups to mount automatically

asm_power_limit??????????????? 1??????????????????? number of processes for disk rebalancing

_asm_ausize??????????????????? 1048576????????????? allocation unit size

_asm_blksize?????????????????? 4096???????????????? metadata block size

_asm_acd_chunks??????????????? 1??????????????????? initial ACD chunks created

_asm_libraries???????????????? ufs????????????????? library search order for discovery

_asm_maxio???????????????????? 1048576????????????? Maximum size of individual I/O request

_asm_allow_only_raw_disks????? TRUE???????????????? Discovery only raw devices

_asmlib_test?????????????????? 0??????????????????? Osmlib test event

NAME?????????????????????????? VALUE??????????????? DESCRIB

------------------------------ -------------------- ------------------------------------------------------------

_asm_allow_resilver_corruption FALSE??????????????? Enable disk resilvering for external redundancy

_asmsid??????????????????????? asm????????????????? ASM instance id

_asm_wait_time???????????????? 18?????????????????? Max/imum time to wait before asmb exits

_asm_stripewidth?????????????? 8??????????????????? ASM file stripe width

_asm_stripesize??????????????? 131072?????????????? ASM file stripe size

_asm_droptimeout?????????????? 60?????????????????? timeout before offlined disks get dropped (in 3s ticks)

_asm_emulmax?????????????????? 10000??????????????? max number of concurrent disks to emulate I/O errors

_asm_emultimeout?????????????? 0??????????????????? timeout before emulation begins (in 3s ticks)

_asm_kfdpevent???????????????? 0??????????????????? KFDP event

20 rows selected.

By eygle on 2009-08-06 12:47 |

Comments (12) |

| 2359 |

12 Comments

沒看清楚, 哪里可以查到 asm_stripesize?

The ASM coarse striping is always equal to the disk group AU size, but fine striping size always remains 128KB in any configuration.(11gR1 doc)

AU is ASM_disk's Unit,

Extent is ASM_File's Unit,

Strip is ASM_File's Strip.

但是怎么理解

_asm_stripewidth 8 ASM file stripe width

呢？

在Oracle 10gR2中，ASM AU的缺省單位大小是1M，相應(yīng)的條帶大小是128K。

在ASM中，可以通過調(diào)整_asm_ausize隱含參數(shù)的大小來進行調(diào)整，_asm_stripesize控制相應(yīng)的條帶化參數(shù)。

請問，ausize和stripesize，磁盤組中磁盤數(shù)目有什么關(guān)系？

_asm_ausize 和磁盤數(shù)目無關(guān)，用戶可以根據(jù)數(shù)據(jù)文件的大小，磁盤組的大小來調(diào)整_asm_ausize設(shè)置，但是通常缺省設(shè)置是足夠的。

如果使用外部磁盤陣列需要考慮stripesize和Raid基本塊大小對齊么？

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