RE: Backups versus snapshots
Date: Thu, 18 Sep 2014 20:54:27 -0700
Message-ID: <00aa01cfd3bd$695e6f70$3c1b4e50$_at_comcast.net>
I worked at one non-tech company that really understood that and they actually mothballed complete systems in warehouses including all SW installation, manuals and company specific documentation with spare parts to ensure they could bring up an old system.
A better approach is to set timelines to refresh your tape media and move data from old media to newer media.
Based on the 90 degree Fahrenheit data center and optimal costing of LTO media and next generation release time frames it is 7 year refresh cycle, so you are not worried about the version library and it is just a part of the process.
It takes time an effort to ensure you have recoverability especially when you are looking at long time frames. We had media at Amazon that was basically considered infinite retention, meaning we would literally keep the data on that media forever for some potential future use.
Matthew Parker
Chief Technologist
425-891-7934 (cell)
Dimensional.dba_at_comcast.net
<http://www.linkedin.com/pub/matthew-parker/6/51b/944/> View Matthew Parker's profile on LinkedIn
From: Chitale, Hemant K [mailto:Hemant-K.Chitale_at_sc.com]
Sent: Thursday, September 18, 2014 8:44 PM
To: dimensional.dba_at_comcast.net
Cc: ORACLE-L
Subject: RE: Backups versus snapshots
The biggest challenge is maintaining the “version” library to support old backups.
How do you maintain the technology to be able to restore old backups ?
- Tape Drives
- Media Management Software libraries
- Operating Systems
- RDBMS Versions
- Admin / Job scripts associated with the OS and Database
Hemant K Chitale
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Dimensional DBA Sent: Friday, September 19, 2014 11:38 AM To: yparesh_at_gmail.com; kmoore_at_zephyrus.com Cc: development_at_the-playground.de; dmarc-noreply_at_freelists.org; 'Seth Miller'; andrew.kerber_at_gmail.com; 'Oracle-L_at_freelists.org' Subject: RE: Backups versus snapshots
I managed backups at Amazon.
If your tapes are truly offsite, such as at Iron Mountain, then the real turn around based on which service level you agreed to from 4 hours to 48 hours to get the media back after you notified Iron Mountain through their website or with a call.
Recovery time after that just became size of the database times a multiplier based on the construction of your system. At Amazon we had rebuilt the backup system from scratch to eliminate bottlenecks and normally restore time was held to about 1.25x of backup time.
In most cases we utilized a system where the backups were sent directly to a tape library in another data center than the database resides in, so it meet the offsite requirement and could immediately start streaming backups at the 1.25x of the backup time. If we had to store tapes outside of the library because of expanding capacity before the new capacity arrived and needed those tapes then it was less than 2 hours to have the tapes back in a tape library.
We had alternate cases where data was long term stored in S3, but it normally took longer up to 2x-2.5x of backup time to restore.
Your mileage will vary depending on your system setup.
I have recovered backups at a variety of clients that were up to 15 years old. Success really depended on how well the media was taken care of while in use and handling of the media in storage, meaning most succeeded but some failed because someone somewhere screwed up in the process..
At amazon where our processes controlled all the steps in usage and storage then actual loss was 4 tapes over 6 years out of ~26K tapes for one of the data center clusters. The failure could be lower, but we over wrote tapes basically every 3 weeks for most database backups, which is significantly more times to write the tapes than any vendor recommends. We also ran the data centers including where the tape libraries were stored at 90 degrees Fahrenheit which helps degrade tape faster than its 30 year generic life span.
There were a variety of long term backups we had held since 1997 and were still able to restore them in 2010.
Matthew Parker
Chief Technologist
425-891-7934 (cell)
Dimensional.dba_at_comcast.net
<http://www.linkedin.com/pub/matthew-parker/6/51b/944/> View Matthew Parker's profile on LinkedIn
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Paresh Yadav
Sent: Thursday, September 18, 2014 7:48 PM
To: kmoore_at_zephyrus.com
Cc: development_at_the-playground.de; dmarc-noreply_at_freelists.org; Seth Miller; andrew.kerber_at_gmail.com; Oracle-L_at_freelists.org
Subject: Re: Backups versus snapshots
Speaking about retention > 30 days. Has anyone actually has done *successful* recall of a backup more than 3 years old and if the backup was found, recovery was succesful i.e. backup media/pieces were good? If yes how much time it took from ordering the recall to recovering the database?
This is a theoretical question but I am very curious to find out what happens to all the tapes that are few years old (physical condition of the tape media, ability to locate them etc.).
Thanks
Paresh
416-688-1003
On Thu, Sep 18, 2014 at 7:01 PM, Keith Moore <kmoore_at_zephyrus.com> wrote:
That’s an interesting question that I’ve asked as well. They have two business units. One keeps backups for 30 days and then they are completely gone. The other business unit keeps them for 10 days and then they are gone. We’ve been asked to restore a copy of a database over 30 days old and had to tell them it couldn’t be done. They now want to reduce the retention to 3 days using archive logs which to me seems rather extreme.
I’ve asked before about keeping monthly and yearly copies, etc but never received any response as to why the policy is what it is.
Keith
On Sep 18, 2014, at 2:22 PM, Martin Bach <development_at_the-playground.de> wrote:
> Just out of interest,
>
> What happens in that case if you have to restore the database system to what it was last month to check if there was a data entry error? That kind of scenario, in addition to longer term archival (think regulators) are my concerns when thinking about snapshot only based approaches. Snapshots before software releases, end of year processing etc sound nice to me though.
>
> Martin
>
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