Thanks for the response. See below

-----Original Message----- From: Penelope Carr [mailto:Penelope.Carr@veritas.com] Sent: 29 August 2001 09:09 To: John Hope-Bailie Subject: RE: Oracle hot backups and snapshots

When you say run into problems retrieving one datafile what do you mean? What tool are you using to do the hot backup? This will determine if you can do what you are asking.

We do the hot backup as described in the NetApp TR 3049, i.e. run a script on the Sun host which does the following ;- 1) Issues an "alter tablespace <name> begin backup" command via sysmgrl for every tablespace (puts them into hot backup mode) 2) Deletes the oldest snapshot on the filer and bumps the others along by 1 (simply renames them) 3) Takes a new snapshot on the filer 4) Issues an "alter tablespace <name> end backup" command via sysmgrl for every tablespace (takes them out of hot backup mode)

We have run a few simple tests thus far for restore of single tablespaces in which we :-

1) Truncated a tablespace to effectively "break" it 2) Took the tablespace offline 3) Recovered the previous version of the relevant data file from the snapshot (by a simple copy) 4) Brought the tablespace online ( All this time the DB and other tablespaces were up)

The tablespace requires media recovery at this point. Once this command is run, it seems to be o.k. with all rows present. I am unsure about what is hapening here. An explanation would be welcome.

When tablespaces are put into backup mode they are all done at once and should not take a huge amount of time to do so. It is the backup that takes longer as the database grows. There is tuning in the database that can be done to help the speed of the backup.

Penelope

Penelope Carr cell 914-439-4911 office 914-934-2404

-----Original Message----- From: John Hope-Bailie [mailto:johnhb@global.co.za] Sent: Wednesday, August 29, 2001 2:19 PM To: toasters@mathworks.com Subject: Oracle hot backups and snapshots

Greetings,

We are trying to utilise a NetApp filer's snapshot feature to enable rapid recovery in an Oracle DB environment.

We are aware of the www.netapp.com/tech_library/3049TR document which covers the basics. The intention is to use the hot backup alternative to create several snapshots throughout the day to provide maximum coverage. Both Oracle 8 and 8i are in use. I have 2 questions :-

1) The TR defines a sequence in which all tablespaces are placed into hot backup mode. It has been suggested that this step might take an extended period of time. Our tests to date have been on relatively small data volumes and the "ALTER TABLESPACE <name> BEGIN BACKUP;" steps have been almost instantaneous. Is it likely that this step would end up taking longer (say tens of minutes) for large DBs ?

2) The system has been set up so that each "customer data set" is defined as a separate schema, many of which are contained within a single database. Each schema contains one or more data files, but these only contain data related to their own schema and not other schemas. The idea here is that if it was necessary to recover data related to one customer, it should be possible to do this without taking any other customer tablespaces offline. During testing we have found that recovering the entire snapshot (with all data files from all schemas) works fine. But when we have recovered only the single datafile related to one schema, we have run into problems. I feel we may be overlooking some basic issue here. Any advice would be welcome.

regards,

John Hope-Bailie

Source Consulting, South Africa email: johnhb@sourceconsulting.co.za