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8 Replies Latest reply: May 4, 2012 4:27 PM by onedbguru RSS

How do we migrate ASM volumes from one physcial disk to another?

934860 Newbie
Currently Being Moderated
All:

We just bought an HP 3PAR Storage Array. Our Storage Team wants to migrate all of our ASM volumes from EMC CLARiiON to HP 3PAR volumes. Is there an ASM command to do that on the fly, such as:

oracleasm migrate <old volume> <new volume>

The UNIX Team can migrate the LVM (mounted) volumes with LVM commands on the fly...

Stuart
  • 1. Re: How do we migrate ASM volumes from one physcial disk to another?
    Levi-Pereira Guru
    Currently Being Moderated
    Hi,


    What's the ASM version?


    It's easy do this job, if you can map the new and old luns on same host. You can perform this work without downtime.

    1) Map New Luns
    2) Configure Permission of New Luns
    3) Add New Lun a existing Diskgroup
    4) After rebalance process finished, remove old Luns from ASM
    5) Remove Luns from host.

    You can do it in one step:
    alter diskgroup <dg_name>
     add disk <path..> ## new luns
     drop disk <asmdisk_name...> ## old asmdisk
    rebalance power 9 wait;
    Or:
    1 Set rebalance power of 0 for diskgroup
    2 Add New Luns
    3 Drop Old Luns
    4 Set rebalance power to 9 for diskgroup with "wait" option
    5 Wait rebalance process finish, so you can remove the old Luns

    Regards,
    Levi Pereira
  • 2. Re: How do we migrate ASM volumes from one physcial disk to another?
    Mike Cuppett Newbie
    Currently Being Moderated
    Stuart,

    You first add the new disk(s) to ASM using a command like 'ALTER DISKGROUP DATA ADD DISK '/dev/rdisk/disk43' NAME DATA_0002, '/dev/rdisk/disk47' NAME DATA_0003 rebalance POWER 5 WAIT;. The rebalance will distribute the existing data evenly across the old and new devices. The new disk(s) should show as cached, member and online in v$asm_disks. You can adjust the rebalance to manage the I/O load impact.

    Then, to remove the old disk(s) use a command like 'ALTER diskgroup DATA DROP DISK 'DATA_0000','DATA_0001' rebalance POWER 5 WAIT;' which will move the data from the old devices onto the new disk(s) evenly and then make the old disk(s) "unused'. The old disk(s) should show a state of 'FORMER' in v$asm_disk.

    I hope this helps.

    Mike

    http://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_1006.htm
  • 3. Re: How do we migrate ASM volumes from one physcial disk to another?
    Levi-Pereira Guru
    Currently Being Moderated
    Hi,
    The UNIX Team can migrate the LVM (mounted) volumes with LVM commands on the fly...
    Yes, he can do that you have to check if it can be done without downtime, because trough ASM you can do it without downtime. This is like a "dd" command will copy bock by block, after finish the mirroring the Lun data must be the same as source including header.

    You will modify Diskstring of ASM by removing old path and adding new path names. Downtime is necessary on this step.

    Levi Pereira
  • 4. Re: How do we migrate ASM volumes from one physcial disk to another?
    934860 Newbie
    Currently Being Moderated
    One more thing: Can you do this in a "crs" cluster?

    Stuart
  • 5. Re: How do we migrate ASM volumes from one physcial disk to another?
    Levi-Pereira Guru
    Currently Being Moderated
    Hi Suart,
    Can you do this in a "crs" cluster?
    What you means "crs" is a clusterware files or RAC database?
    If you means clusterware files, it will depend of version of your clusterware.
    If it a RAC Database files, the procedure is the same as described.

    Levi Pereira
  • 6. Re: How do we migrate ASM volumes from one physcial disk to another?
    onedbguru Pro
    Currently Being Moderated
    Levi Pereira wrote:
    Hi,
    >
    Or:
    1 Set rebalance power of 0 for diskgroup
    2 Add New Luns
    3 Drop Old Luns
    4 Set rebalance power to 9 for diskgroup with "wait" option
    5 Wait rebalance process finish, so you can remove the old Luns
    At one of my previous employers, we used this method to move 250TB+ worth of storage from one vendor to another - Works GREAT!!! especially if you have a LOT of HBA's and multipathing that actually works... (like on a SUN 6900 with 8 HBA's) Except - we did NOT use the WAIT parameter. The thing ran in the background for 27days. Oracle said: "theoretically it should work - but we have never tried it on something that big". We did - IN PRODUCTION. Oh, we were also loading 1TB/day while it was running.

    >
    Regards,
    Levi Pereira
  • 7. Re: How do we migrate ASM volumes from one physcial disk to another?
    Levi-Pereira Guru
    Currently Being Moderated
    Hi,

    I honestly do not have the courage to do something so big in just a process.
    If I was the DBA of this environment I would break the process into sections.

    For example:
    250TB = 500 Luns
    500Luns/20 sections = 25 Luns

    So, I can migrate 25 Lun/ ~12TB a time.

    This way if any problem occurs I can take the action.

    Regards,
    Levi Pereira
  • 8. Re: How do we migrate ASM volumes from one physcial disk to another?
    onedbguru Pro
    Currently Being Moderated
    We did actually do it in 3 sections as you can only do one diskgroup rebalance at a time. Our largest diskgroup was still quite large - our LUNS were 1.5TB.

    The entire operation took 27 days. At day 20-ish, in the middle of the 2nd diskgroup, the primary ASM instance crashed. Database was still up, ASM switched to node 2 and kept going. Only one small problem. Before the crash, it was processing in excess of 300G/hr. After the crash while processing on node2 it was doing roughly 5G/hr. After 6 hours and having resolved the problem with the ASM instance on the primary node, we purposely forced ASM back to the primary node. The performance returned to 300G+/hr. All of this online with no database downtime - while loading 1TB/day and thousands of DSS-type queries.

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