Database Reference
In-Depth Information
be assigned to failure groups, which indicate the storage system topology to ASM, such that
mirrored copies can be placed on different storage arrays or may be accessed using different
host bus adapters.
For readers who would like to familiarize themselves with ASM, but do not have access to
a SAN or cannot create raw devices on a local disk due to space constraints or lack of privileges,
this chapter demonstrates how to set up a test environment for automatic storage management
on Windows with cooked files and _ASM_ALLOW_ONLY_RAW_DISKS . Old school UNIX jargon distin-
guished raw files from cooked files. Cooked files are simply the opposite of raw devices—files in a
file system. After all, something that's not raw has to be cooked, right?
ASM Hidden Parameters
Undocumented parameters pertaining to ASM may be retrieved by running the following
query as user SYS:
SQL> SELECT x.ksppinm name, y.ksppstvl value, x.ksppdesc description
FROM x$ksppi x, x$ksppcv y
WHERE x.inst_id = userenv('Instance')
AND y.inst_id = userenv('Instance')
AND x.indx = y.indx
AND x.ksppinm LIKE '\_asm%' ESCAPE '\'
ORDER BY name;
NAME VALUE DESCRIPTION
------------------------------ ---------- -----------------------------------
_asm_acd_chunks 1 initial ACD chunks created
_asm_allow_only_raw_disks TRUE Discovery only raw devices
_asm_allow_resilver_corruption FALSE Enable disk resilvering for
external redundancy
_asm_ausize 1048576 allocation unit size
_asm_blksize 4096 metadata block size
_asm_disk_repair_time 14400 seconds to wait before dropping a
failing disk
_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
_asm_libraries ufs library search order for discovery
_asm_maxio 1048576 Maximum size of individual I/O
request
_asm_stripesize 131072 ASM file stripe size
_asm_stripewidth 8 ASM file stripe width
_asm_wait_time 18 Max/imum time to wait before asmb
exits
_asmlib_test 0 Osmlib test event
_asmsid asm ASM instance id
 
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