Re: UNIX root backup/SAN disk image vs. Oracle Hot Backups

On 2004-09-18, Howard J. Rogers <hjr_at_dizwell.com> wrote:
> JEDIDIAH wrote:
>
>> On 2004-09-01, Howard J. Rogers <hjr_at_dizwell.com> wrote:
>>> Frank Foss wrote:
>>>
>>>>
>>>> "Ibrahim DOGAN" <idogan_tech_at_yahoo.com> wrote in message
>>>> news:6bf58828.0409010559.5ccd70bb_at_posting.google.com...
>>>>> Can UNIX root backup or SAN disk image backup be reliable as Oracle
>>>>> database backup?
>>>>>
>>>>> I don't know internals about root backup or disk images but it sounds
>>>>> like you may end up with inconsistent control file/datafiles when you
>>>>> load them back .
>>>>>
>>>>> is there anybody out there who knows how root backup/disk image works
>>>>> and can tell whether they can replace Oracle hot backups?
>>>>
>>>> The concept is developed to reduce the downtime for a cold backup.
>>>> A SAN disk image (EMC calls it Business Contingency Volume --BCV)
>>>> is an identical synchronized copy of your live filesystem at a point in
>>>> time. The connection between the two is broken off, and the live
>>>> filesystem goes along doing its thing, while the BCV is static.
>> [deletia]
>>>
>>> I've nothing much to add except that if you're going to break a mirror in
>>> order to grab a backup, you don't actually have to shut the database down
>>> but can instead use the suspend (and resume) statements.
>>
>> Why not just put all the tablespaces in backup mode?
>
>
> How many tablespaces have you got?
>
> So how long do you think it would take you to put all of them into hot
> backup mode?
>
> (And whereas your answer might be "seconds", someone else's might be
> "minutes").
>
> And all the time you're trying to get all of them into hot backup mode, the
> first ones that got there are generating block-sized redo.
>
> That's why.

        ...which all should be less of a problem if you have a disk backup mechanism which is near instant.

        The problem of "oh my god, my talblespaces are in hot backup mode" is a problem that Oracle has already supposedly solved. It's not uncommon for more conventional backup practices to keep a tablespace in backup mode for minutes. So that alone isn't necessarily a problem.

        Typically, shutting down for a cold backup is considered far more problematic.

[deletia]

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