[Info-vax] File Systems

[Jan-Erik Soderholm]

Stephen Hoffman skrev den 2015-03-06 14:39:
> On 2015-03-06 03:22:14 +0000, JF Mezei said:
>
>> On 15-03-05 14:46, Stephen Hoffman wrote:
>>
>>> Or consistent, continuous, online backups,
>>
>>
>> How about using volume shadowing where one member is a special member
>> with differeent low level driver and its role is just to receive all
>> writes and update a "backup save set" in real time ?
>
> This can be viewed as is a way to push the equivalent of a BACKUP
> /IGNORE=INTERLOCK "backup" down closer to the storage controller level, or
> a way to push a (bad) storage-level backup up into HBVS.
>
> Applications almost invariably use more than one disk, so you'll have to
> capture and coordinate the I/O across all of the storage devices the
> application(s) use....

Yes, this will be hard for any backup on regualr files where there
is no syncronisation over the whole filesystem.

If this is a real concern it might be better to store your
data that must have consistent backups in a database.

Rdb have never had any problem with this, either regarding
having transaction consistent online backups or that the data
is on multiple physical disks. Your data (tables) are always
consistend over all tables and all disk volumes.

Jan-Erik.