snapshot task and snapshot volume capacity planning

[strategist922]

Hi folks,

We have purchased Open-E DSS V6 unlimited capacity license.
It seems work fine now. But we have some question about the
snapshot function.

This storage system has 3TB HDD * 16 with RAID-6 configuration
(with Areca ARC-1880). Now, there are 7 data volume on the system,
detail size are as following:

Volume1：2 TB
Volume2：2 TB
Volume3：2 TB
Volume4：10 TB
Volume5：1 TB
Volume6：10 TB
Volume7：1 TB

For Volume1 and Volume2, we need keep not only snapshot take on everyday's 00:00
but also keep snapshot take on the latest day's 06:00, 13:00, and 18:00. In this case
we need 10 snapshot volume for Volume1 and 10 snapshot for Volume2,am I right?

For Volume3, Volume4, Volume5, Volume6, and Volume7, we only want to keep the
latest 3 day's snapshot. For example, today is 2011/11/16, we only want to keep sanpshot take on 2011/11/15 00:00, 2011/11/14 00:00 and 2011/11/13 00:00.
Can anyone tell me how to set snapshot task for these volume?

When create schedule for snapshot, task system will ask me to set the start/stop
time for the schedule snapshot task, I know the start time to start the snapshot task,
but how can I know the stop time? (i.e. I don't know system need how long to complete
the task!)

And, how can I determinate the snapshot volume size for specific volume? (i.e. In my system, Volume4 is a 10TB volume, what is the proper size for its snapshot volume? )

Thanks in advance!

[To-M]

In short - the Snapshot should be 3 times the amount of changes you anticipate to accrue with the volume you are writing to, so if you have a 1TB volume and you expect to have 50GB for that day then a 150GB Snapshot volume will be best. Please find the following links that will help you to know more about Snapshot.

http://kb.open-e.com/Snapshot_159.html

http://kb.open-e.com/How-do-snapshot...cation_49.html

http://kb.open-e.com/How-do-snapshot...-task_102.html

http://www.open-e.com/service-and-su...-to-resources/
Open-E Snapshots:
2010.12 Description of Open-E Snapshot

[strategist922]

In short - the Snapshot should be 3 times the amount of changes you anticipate to accrue with the volume you are writing to, so if you have a 1TB volume and you expect to have 50GB for that day then a 150GB Snapshot volume will be best. Please find the following links that will help you to know more about Snapshot.

http://kb.open-e.com/Snapshot_159.html

http://kb.open-e.com/How-do-snapshot...cation_49.html

http://kb.open-e.com/How-do-snapshot...-task_102.html

http://www.open-e.com/service-and-su...-to-resources/
Open-E Snapshots:
2010.12 Description of Open-E Snapshot

Thanks for your information about snapshot of Open-E
I read the document, and it show me the following limitation:
10 sanpshots per LV
20 sanpshots per system

Could it possible to increase the default limitation value?
As mention in previous question, we have 7 volume and need more than 20 active schedule snapshots!

Best Regards!
Best Regards!