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22 January, 2017

12cR1 RAC Posts -- 4 : Adding a Disk of a different size

How does 12.1.0.2 ASM handle adding a disk of a different size to an existing DiskGroup ?

I currently have 4 disks of 5GB each in 2 DiskGroups

[oracle@collabn1 ~]$ sqlplus / as sysasm

SQL*Plus: Release 12.1.0.2.0 Production on Sat Jan 21 23:48:00 2017

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Real Application Clusters and Automatic Storage Management options

SQL> select group_number, disk_number, name, state, total_mb
  2  from v$asm_disk
  3  order by 1,2,3
  4  /

GROUP_NUMBER DISK_NUMBER NAME                           STATE      TOTAL_MB
------------ ----------- ------------------------------ -------- ----------
           0           0                                NORMAL            0
           1           0 DATA_0000                      NORMAL         5114
           1           1 DATA_0001                      NORMAL         5114
           2           0 FRA_0000                       NORMAL         5114

SQL>
SQL> select group_number, name
  2  from v$asm_diskgroup
  3  order by 1
  4  /

GROUP_NUMBER NAME
------------ ------------------------------
           1 DATA
           2 FRA

SQL>


The DATA DiskGroup has 2 disks of 5GB each and the FRA DiskGroup has 1 disk of 5GB.  One disk (identified as DiskNumber=0) is not yet assigned.

What happens if I try to expand the DATA DiskGroup with a Disk of 10GB ?

[root@collabn1 dev]# fdisk /dev/sdf
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xff8b0ab7.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition
   l   list known partition types
   m   print this menu
   n   add a new partition
   o   create a new empty DOS partition table
   p   print the partition table
   q   quit without saving changes
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit
   x   extra functionality (experts only)

Command (m for help): p

Disk /dev/sdf: 12.9 GB, 12884901888 bytes
255 heads, 63 sectors/track, 1566 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xff8b0ab7

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1566, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1566, default 1566):
Using default value 1566

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
[root@collabn1 dev]#
[root@collabn1 dev]# /sbin/scsi_id -g -u -d /dev/sdf
1ATA_VBOX_HARDDISK_VB535deca9-9a295efe
[root@collabn1 dev]#
[root@collabn1 dev]# cd /etc/udev/rules.d
[root@collabn1 rules.d]# vi 99-oracle-asmdevices.rules
[root@collabn1 rules.d]# tail -1 99-oracle-asmdevices.rules
KERNEL=="sd?1", BUS=="scsi", PROGRAM=="/sbin/scsi_id -g -u -d /dev/$parent",  RESULT=="1ATA_VBOX_HARDDISK_VB535deca9-9a295efe", NAME="asm-disk5", OWNER="oracle", GROUP="dba", MODE="0660"
[root@collabn1 rules.d]#
[root@collabn1 rules.d]# /sbin/partprobe /dev/sdf1
[root@collabn1 rules.d]# /sbin/udevadm test /block/sdb/sdf1
run_command: calling: test
udevadm_test: version 147
This program is for debugging only, it does not run any program,
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

parse_file: reading '/lib/udev/rules.d/10-console.rules' as rules file
parse_file: reading '/lib/udev/rules.d/10-dm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/11-dm-lvm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/13-dm-disk.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-isdn.rules' as rules file
parse_file: reading '/lib/udev/rules.d/40-redhat.rules' as rules file
parse_file: reading '/lib/udev/rules.d/42-qemu-usb.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-firmware.rules' as rules file
parse_file: reading '/lib/udev/rules.d/50-udev-default.rules' as rules file
parse_file: reading '/etc/udev/rules.d/55-usm.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-alias-kmsg.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-cdrom_id.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-fprint-autosuspend.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-net.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-pcmcia.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-input.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-serial.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage-tape.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-v4l.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-raw.rules' as rules file
parse_file: reading '/etc/udev/rules.d/60-vboxadd.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-mobile-action.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-option-modem-modeswitch.rules' as rules file
parse_file: reading '/lib/udev/rules.d/61-persistent-storage-edd.rules' as rules file
parse_file: reading '/lib/udev/rules.d/64-device-mapper.rules' as rules file
parse_file: reading '/lib/udev/rules.d/64-md-raid.rules' as rules file
parse_file: reading '/lib/udev/rules.d/65-md-incremental.rules' as rules file
parse_file: reading '/lib/udev/rules.d/69-dm-lvm-metad.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-acl.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-cups-libusb.rules' as rules file
parse_file: reading '/lib/udev/rules.d/70-hid2hci.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-cd.rules' as rules file
parse_file: reading '/etc/udev/rules.d/70-persistent-net.rules' as rules file
parse_file: reading '/lib/udev/rules.d/71-biosdevname.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-cd-aliases-generator.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-net-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-persistent-net-generator.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-tty-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/78-sound-card.rules' as rules file
parse_file: reading '/lib/udev/rules.d/79-fstab_import.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-drivers.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-iosched.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-mpath-iosched.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-regulatory.rules' as rules file
parse_file: reading '/lib/udev/rules.d/88-clock.rules' as rules file
parse_file: reading '/lib/udev/rules.d/89-microcode.rules' as rules file
parse_file: reading '/etc/udev/rules.d/90-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/90-btrfs.rules' as rules file
parse_file: reading '/etc/udev/rules.d/90-hal.rules' as rules file
parse_file: reading '/lib/udev/rules.d/91-drm-modeset.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-dm-notify.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-keyboard-force-release.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-keymap.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-udev-late.rules' as rules file
parse_file: reading '/etc/udev/rules.d/98-kexec.rules' as rules file
parse_file: reading '/etc/udev/rules.d/99-oracle-asmdevices.rules' as rules file
parse_file: reading '/dev/.udev/rules.d/99-root.rules' as rules file
udev_rules_new: rules use 32448 bytes tokens (2704 * 12 bytes), 19085 bytes buffer
udev_rules_new: temporary index used 19500 bytes (975 * 20 bytes)
unable to open device '/sys/block/sdb/sdf1'
[root@collabn1 rules.d]#
[root@collabn1 rules.d]# /sbin/udevadm control --reload-rules
[root@collabn1 rules.d]# /sbin/start_udev
Starting udev:                                             [  OK  ]
[root@collabn1 rules.d]# 
[root@collabn1 rules.d]# ls -l /dev/asm*
brw-rw----. 1 oracle dba 8, 17 Jan 22 00:07 /dev/asm-disk1
brw-rw----. 1 oracle dba 8, 33 Jan 22 00:07 /dev/asm-disk2
brw-rw----. 1 oracle dba 8, 49 Jan 22 00:07 /dev/asm-disk3
brw-rw----. 1 oracle dba 8, 65 Jan 22 00:05 /dev/asm-disk4
brw-rw----. 1 oracle dba 8, 81 Jan 22 00:05 /dev/asm-disk5


So I now have asm-disk5 as the new ASM Disk.  Let my try to add this disk.

SQL> set pages600
SQL> select group_number, disk_number, name, path, total_mb
  2  from v$asm_disk
  3  order by 1,2
  4  /

GROUP_NUMBER DISK_NUMBER NAME
------------ ----------- ------------------------------
PATH
--------------------------------------------------------------------------------
  TOTAL_MB
----------
           0           0
/dev/asm-disk5
         0

           0           1
/dev/asm-disk4
         0

           1           0 DATA_0000
/dev/asm-disk1
      5114

           1           1 DATA_0001
/dev/asm-disk2
      5114

           2           0 FRA_0000
/dev/asm-disk3
      5114


SQL>
SQL> alter diskgroup data add disk '/dev/asm-disk5';

Diskgroup altered.

SQL>
SQL> select group_number, name, total_mb
  2  from v$asm_diskgroup
  3  order by 1,2
  4  /

GROUP_NUMBER NAME                             TOTAL_MB
------------ ------------------------------ ----------
           1 DATA                                22512
           2 FRA                                  5114

SQL>
SQL> select group_number, name, type
  2  from v$asm_diskgroup
  3  order by 1,2
  4  /

GROUP_NUMBER NAME                           TYPE
------------ ------------------------------ ------
           1 DATA                           EXTERN
           2 FRA                            EXTERN

SQL>
SQL> select group_number, name, compatibility, database_compatibility
  2  from v$asm_diskgroup
  3  order by 1
  4  /

GROUP_NUMBER NAME
------------ ------------------------------
COMPATIBILITY
------------------------------------------------------------
DATABASE_COMPATIBILITY
------------------------------------------------------------
           1 DATA
12.1.0.0.0
10.1.0.0.0

           2 FRA
12.1.0.0.0
10.1.0.0.0


SQL>
SQL> select group_number, disk_number, name, path, total_mb
  2  from v$asm_disk
  3  order by 1,2,3
  4  /

GROUP_NUMBER DISK_NUMBER NAME
------------ ----------- ------------------------------
PATH
--------------------------------------------------------------------------------
  TOTAL_MB
----------
           0           0
/dev/asm-disk4
         0

           1           0 DATA_0000
/dev/asm-disk1
      5114

           1           1 DATA_0001
/dev/asm-disk2
      5114

           1           2 DATA_0002
/dev/asm-disk5
     12284

           2           0 FRA_0000
/dev/asm-disk3
      5114


SQL>


According to Oracle Support Document 1938950.1, adding a disk of a different size to an existing DiskGroup fails with an error ORA-15410 in 12.1.0.2.  However, that seems to apply to NORMAL or HIGH Redundancy and COMPATIBLE.ASM 12.1.0.2.   Here, I have EXTERNAL Redundancy and COMPATIBLE.ASM 12.1.0.0.0

Do I recommend Disks of different sizes ?  Absolutely *not* in Production.  This is a "play" environment in Virtual Machines on my desktop that I can destroy and recreate anytime.  I can monitor disk usage as well.
.
.
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2 comments:

Gabi Draghici said...

Yet, we can have situations where diff. disk sizes should be allowed ...
As stated in https://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#OSTMG94134 :
"....
There might be situations where it is acceptable to temporarily have disks of different sizes and performance characteristics coexist in a disk group. This would be the case when migrating from an old set of disks to a new set of disks. ...."
Now, how is this supposed to be done in 12C ?

prathibha said...

Hi,
Thanks for posting such an useful article on disks. i got some new knowledge on reading this article today.
Thank you.

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