ADSM-L

Re: [ADSM-L] sector-based incremental backup of filesystem

2010-01-23 11:13:24
Subject: Re: [ADSM-L] sector-based incremental backup of filesystem
From: Josh Davis <xaminmo AT OMNITECH DOT NET>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Sat, 23 Jan 2010 08:11:14 -0800
For now, the best you could hope for would be an image mode snapshot backup 
going into a deduplicated storage pool.


Alternatively, if your application has a TSM connect agent (such as TDP for 
Databases), then you could use that to get the application data incrementally 
rather than pulling the blocks.

Otherwise, if you have a home-made application, it shouldn't be hard to write 
an incremental image backup tool.

Use OS and/or Array commands to:
* Quiesce the filesystem
* Lock writes
* snapshot
* resume r/w
* present the snapshot devices

Then, using the code from adsmpipe, hash procedures, and standard file I/O:
* Try to pull an existing hash table out of TSM.  Backup 0 would have none.
* Tead in the snapshot raw logical volume and generate hashes for every block.
* For any block without a hash, write out in binary format the sector offset, 
number of blocks, and then the raw data
* Once the whole "image" is written, then you can save the hash table as a 
second file.
* If you wanted to be fancy, you could index by hash and gain some manner of 
block-level dedupe.

Finally, you'd destroy the filesystem snapshot if necessary.

Hash code and file I/O code are readily available on the internet.  adsmpipe 
can also be found on the internet.
I would recommend static linking if your UNIX of choice prefers it.  On Linux, 
ADSMPIPE is very sensitive to libc changes.

As for something like FastBack Mounter, you'd need to write a block level 
device driver, which is more complicated.



________________________________
From: Mehdi Salehi <iranian.aix.support AT GMAIL DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Sent: Sat, January 23, 2010 1:34:40 AM
Subject: [ADSM-L] sector-based incremental backup of filesystem

Hi,
Is there any way for sector-based incremental image backup in Unix systems?
B/A client helps incremental-by-date, but it is inefficient for some
applications. What I am looking for is a feature like what FastBack or
UltraBac present for Windows.

Thanks

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