Go Premium for a chance to win a PS4. Enter to Win

x
?
Solved

PIT - point in time copy

Posted on 2012-03-12
5
Medium Priority
?
520 Views
Last Modified: 2012-08-14
Hi,

How does PIT works? For an example if I have source volume and target voume, how does PIT work? First it copies the data from source to target, and then monitor the changes and once there is a change, it copies the data?
0
Comment
Question by:mokkan
  • 3
  • 2
5 Comments
 
LVL 68

Assisted Solution

by:woolmilkporc
woolmilkporc earned 2000 total points
ID: 37713592
There are many implementations of PIT copy, such as "split mirror", "snapshot", "flash copy"  etc.

This is a Whitepaper from the 2002 Storage Conference outlining the common approaches and giving some insight into their functional principles:

http://www.storageconference.org/2002/papers/d05bp-aaz.pdf

"2002" seems a long time ago, but the basic concepts mentioned in the paper are still valid (and in use) nonetheless.

wmp
0
 

Author Comment

by:mokkan
ID: 37720344
Thank you, I read it but not getting the full concept. It is basically keep track of the changes  perdiatically?
0
 
LVL 68

Assisted Solution

by:woolmilkporc
woolmilkporc earned 2000 total points
ID: 37720380
It always keeps track of all changes, because every I/O must be intercepted.

Depending on the implementation changes are recorded in a flash area while the original keeps unchanged, or the changes are applied to the original while a "before image" of the original is copied to the flash area.
0
 

Author Comment

by:mokkan
ID: 37720435
For an example if the data  corrupted and if I want to decide the restore data, can I get pick a time?
0
 
LVL 68

Accepted Solution

by:
woolmilkporc earned 2000 total points
ID: 37720475
Not with the mentioned flash/snapshot technologies.
You must decide whether to use the unchanged original originating from the time where the snapshot was initiated, or to use the updated copy.
Of course you can initiate several snapshots periodically, so you can decide which one is still good and which one is corrupted.

It seems what you're talking about is rather some kind of asynchronous (delayed) replication, where you can stop the replication in a certain time window once you noticed that corruption has occurred. You can then continue using the replica, which is still good given you actually hit the time window to stop the replication.
0

Featured Post

NEW Veeam Backup for Microsoft Office 365 1.5

With Office 365, it’s your data and your responsibility to protect it. NEW Veeam Backup for Microsoft Office 365 eliminates the risk of losing access to your Office 365 data.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Many businesses neglect disaster recovery and treat it as an after-thought. I can tell you first hand that data will be lost, hard drives die, servers will be hacked, and careless (or malicious) employees can ruin your data.
Steps to fix error: “Couldn’t mount the database that you specified. Specified database: HU-DB; Error code: An Active Manager operation fail”
This tutorial will show how to configure a single USB drive with a separate folder for each day of the week. This will allow each of the backups to be kept separate preventing the previous day’s backup from being overwritten. The USB drive must be s…
Despite its rising prevalence in the business world, "the cloud" is still misunderstood. Some companies still believe common misconceptions about lack of security in cloud solutions and many misuses of cloud storage options still occur every day. …

877 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question