RE: Backups versus snapshots
- From: "Chitale, Hemant K" <Hemant-K.Chitale@xxxxxx>
- To: <dimensional.dba@xxxxxxxxxxx>
- Date: Fri, 19 Sep 2014 11:43:35 +0800
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 ?
1. Tape Drives
2. Media Management Software libraries
3. Operating Systems
4. RDBMS Versions
5. Admin / Job scripts associated with the OS and Database
Hemant K Chitale
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Dimensional DBA
Sent: Friday, September 19, 2014 11:38 AM
To: yparesh@xxxxxxxxx; kmoore@xxxxxxxxxxxx
Cc: development@xxxxxxxxxxxxxxxxx; dmarc-noreply@xxxxxxxxxxxxx; 'Seth Miller';
andrew.kerber@xxxxxxxxx; 'Oracle-L@xxxxxxxxxxxxx'
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@xxxxxxxxxxx
View Matthew Parker's profile on LinkedIn
<http://www.linkedin.com/pub/matthew-parker/6/51b/944/>
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Paresh Yadav
Sent: Thursday, September 18, 2014 7:48 PM
To: kmoore@xxxxxxxxxxxx
Cc: development@xxxxxxxxxxxxxxxxx; dmarc-noreply@xxxxxxxxxxxxx; Seth Miller;
andrew.kerber@xxxxxxxxx; Oracle-L@xxxxxxxxxxxxx
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@xxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxx> 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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