“Everything should be made as simple as possible, but not simpler.” – Albert Einstein
I am curious as to why anyone would use ASM for a standalone database as it introduce more complexity of having to install, maintain, and upgrade Grid Infrastructure.
I asked the DBAs and here are the some responses:
ASM always bypass the OS caching layer (direct IO) which can be difficult and inconsistent using traditional FS.
ASM allows move to another type of storage in the future.
ASM provides transparent balance and migration between any type of block storage.
ASM provides online operations like adding/removing/resizing disks/LUNs from one disk array to another.
I asked a former manager who knows EMC storage and Solaris and here are his responses:
1. OS Caching: this was solved a long time ago. As you know, even plain old UFS on Solaris has been able to do this for years with Oracle.
2. Moving to another type of storage. That’s a function of either the volume manager on the OS or the array itself (both are possible and depend on your setup).
Oracle isn’t bringing anything new to the table with ASM.
3. Balance and migration. Again, a function of the volume manager and/or the array. Nothing new being done by ASM.
4. Online operations and migrations. Again, a function of the volume manager and/or the array. ASM brings nothing new.It seems to me that ASM does, really, one thing: it eliminates the OS volume manager but at the same time expands the scope of the DBA to now include storage problems. That sounds like a distraction to me.
I would love to see a live debate on this.
Still not 100% satisfied, I started to research and explore ASM online operations.
ASM disks VENDOR101,VENDOR102,VENDOR103 are mapped to /dev/sdb1,/dev/sdc1,/dev/sdd1
[root@looney ~]# ls -l /dev/sd* brw-rw---- 1 root disk 8, 0 Nov 23 09:23 /dev/sda brw-rw---- 1 root disk 8, 1 Nov 23 09:23 /dev/sda1 brw-rw---- 1 root disk 8, 2 Nov 23 09:23 /dev/sda2 brw-rw---- 1 root disk 8, 16 Nov 23 09:23 /dev/sdb brw-rw---- 1 root disk 8, 17 Nov 23 09:25 /dev/sdb1 brw-rw---- 1 root disk 8, 32 Nov 23 09:23 /dev/sdc brw-rw---- 1 root disk 8, 33 Nov 23 09:27 /dev/sdc1 brw-rw---- 1 root disk 8, 48 Nov 23 09:23 /dev/sdd brw-rw---- 1 root disk 8, 49 Nov 23 09:27 /dev/sdd1 brw-rw---- 1 root disk 8, 64 Nov 23 09:23 /dev/sde brw-rw---- 1 root disk 8, 65 Nov 23 09:23 /dev/sde1 brw-rw---- 1 root disk 8, 80 Nov 23 09:23 /dev/sdf brw-rw---- 1 root disk 8, 81 Nov 23 09:23 /dev/sdf1 brw-rw---- 1 root disk 8, 96 Nov 23 09:23 /dev/sdg brw-rw---- 1 root disk 8, 97 Nov 23 09:23 /dev/sdg1 [root@looney ~]# ls -l /dev/oracleasm/disks/ total 0 brw-rw---- 1 oracle dba 8, 17 Nov 23 09:25 VENDOR101 brw-rw---- 1 oracle dba 8, 33 Nov 23 09:27 VENDOR102 brw-rw---- 1 oracle dba 8, 49 Nov 23 09:27 VENDOR103 [root@looney ~]# /etc/init.d/oracleasm listdisks VENDOR101 VENDOR102 VENDOR103 [root@looney ~]# /etc/init.d/oracleasm querydisk -p VENDOR101 Disk "VENDOR101" is a valid ASM disk /dev/sdb1: LABEL="VENDOR101" TYPE="oracleasm" [root@looney ~]# /etc/init.d/oracleasm querydisk -p VENDOR102 Disk "VENDOR102" is a valid ASM disk /dev/sdc1: LABEL="VENDOR102" TYPE="oracleasm" [root@looney ~]# /etc/init.d/oracleasm querydisk -p VENDOR103 Disk "VENDOR103" is a valid ASM disk /dev/sdd1: LABEL="VENDOR103" TYPE="oracleasm"
Create ASM disks for VENDOR201,VENDOR202,VENDOR203 using /dev/sde1,/dev/sdf1,/dev/sdg1
[root@looney ~]# /etc/init.d/oracleasm createdisk 'vendor201' /dev/sde1 Marking disk "vendor201" as an ASM disk: [ OK ] [root@looney ~]# /etc/init.d/oracleasm createdisk 'vendor202' /dev/sdf1 Marking disk "vendor202" as an ASM disk: [ OK ] [root@looney ~]# /etc/init.d/oracleasm createdisk 'vendor203' /dev/sdg1 Marking disk "vendor203" as an ASM disk: [ OK ] [root@looney ~]#
Perform ASM ONLINE Migration
Query ASM disks:
SYS@+ASM> @asmdisk
INST_ID PATH DISK_NAME GROUP_NUMBER GROUP_NAME STATE TYPE TOTAL_GB FREE_GB
---------- -------------------- --------------- ------------ --------------- ---------- ---------- ---------- ----------
1 ORCL:VENDOR101 VENDOR101 1 DATA1 MOUNTED EXTERN 14.98 13.27
1 ORCL:VENDOR102 VENDOR102 1 DATA1 MOUNTED EXTERN 14.98 13.27
1 ORCL:VENDOR103 VENDOR103 1 DATA1 MOUNTED EXTERN 14.98 13.27
1 ORCL:VENDOR201
1 ORCL:VENDOR202
1 ORCL:VENDOR203
6 rows selected.
Add new disks / Drop old disks from ASM diskgroup:
ASM power limit ranges from 1-11.
In the demonstration, power limit 1 was used to be able to query progress from v$asm_operation
SYS@+ASM> alter diskgroup DATA1 add disk 'ORCL:VENDOR201','ORCL:VENDOR202','ORCL:VENDOR203' drop disk 'VENDOR101','VENDOR102','VENDOR103' rebalance power 1; 2 3 4 Diskgroup altered. SYS@+ASM> SYS@+ASM> @asmop GROUP_NUMBER OPERA STATE POWER ACTUAL SOFAR EST_WORK EST_RATE EST_MINUTES ERROR_CODE ------------ ----- ---------- ---------- ---------- ---------- ---------- ---------- ----------- -------------------------------------------- 1 REBAL RUN 1 1 58 1756 60 28 SYS@+ASM> r 1* select * from v$asm_operation GROUP_NUMBER OPERA STATE POWER ACTUAL SOFAR EST_WORK EST_RATE EST_MINUTES ERROR_CODE ------------ ----- ---------- ---------- ---------- ---------- ---------- ---------- ----------- -------------------------------------------- 1 REBAL RUN 1 1 178 1758 677 2 SYS@+ASM> r 1* select * from v$asm_operation GROUP_NUMBER OPERA STATE POWER ACTUAL SOFAR EST_WORK EST_RATE EST_MINUTES ERROR_CODE ------------ ----- ---------- ---------- ---------- ---------- ---------- ---------- ----------- -------------------------------------------- 1 REBAL RUN 1 1 298 1759 697 2 SYS@+ASM> r 1* select * from v$asm_operation no rows selectedSYS@+ASM> @asmdisk INST_ID PATH DISK_NAME GROUP_NUMBER GROUP_NAME STATE TYPE TOTAL_GB FREE_GB ---------- -------------------- --------------- ------------ --------------- ---------- ---------- ---------- ---------- 1 ORCL:VENDOR101 1 ORCL:VENDOR102 1 ORCL:VENDOR103 1 ORCL:VENDOR201 VENDOR201 1 DATA1 MOUNTED EXTERN 14.98 13.27 1 ORCL:VENDOR202 VENDOR202 1 DATA1 MOUNTED EXTERN 14.98 13.27 1 ORCL:VENDOR203 VENDOR203 1 DATA1 MOUNTED EXTERN 14.98 13.27 6 rows selected. SYS@+ASM>
Delete ASM disks for /dev/sdb1, dev/sdd1, /dev/sdd1
[root@looney ~]# /etc/init.d/oracleasm deletedisk /dev/sdb1
Removing ASM disk "/dev/sdb1": [ OK ]
[root@looney ~]# /etc/init.d/oracleasm deletedisk /dev/sdc1
Removing ASM disk "/dev/sdc1": [ OK ]
[root@looney ~]# /etc/init.d/oracleasm deletedisk /dev/sdd1
Removing ASM disk "/dev/sdd1": [ OK ]
[root@looney ~]# /etc/init.d/oracleasm scandisks
Scanning the system for Oracle ASMLib disks: [ OK ]
[root@looney ~]# /etc/init.d/oracleasm listdisks
VENDOR201
VENDOR202
VENDOR203
SYS@+ASM> @asmdisk
INST_ID PATH DISK_NAME GROUP_NUMBER GROUP_NAME STATE TYPE TOTAL_GB FREE_GB
---------- -------------------- --------------- ------------ --------------- ---------- ---------- ---------- ----------
1 ORCL:VENDOR201 VENDOR201 1 DATA1 MOUNTED EXTERN 14.98 13.27
1 ORCL:VENDOR202 VENDOR202 1 DATA1 MOUNTED EXTERN 14.98 13.27
1 ORCL:VENDOR203 VENDOR203 1 DATA1 MOUNTED EXTERN 14.98 13.27
SYS@+ASM>
Would you used ASM for single instance database? Why or Why not?
