topic Re: Business Copy EVA problem in Disk Enclosures

Business Copy EVA problem

Jerry Tsai — Thu, 08 Jul 2004 11:08:54 GMT

Hi:

Could anyone provide some comments for the following questions about BC EVA?

- As I know, snapshot will exist in the same disk group with source Vdisk. If the total EVA space is 250G (one disk group), a 100G Vdisk with mirror was created. It means 200G of total EVA space used, and 50G is free. When we make a snap BCV, does this BCV can only use the available 50G space? so I can not use the "fully Allocated Snapshot". right?

- What is best practice for mirror and BCV?

- If the source data does not change, is the size of the BCV vdiisk always zero?

- Where is the scheduling function within BC GUI?

Thanks for any response.

Re: Business Copy EVA problem

Jason Webster — Thu, 08 Jul 2004 13:32:53 GMT

If you create a 100G mirrored Vdisk, thats how big the Vdisk is. It does not allocate another 100GB because you mirrored the Vdisk. Also, as long as the data does not change, a SNAP that is not a "fully allocated Snapshot" will not take up any space. There is not scheduling function that I know of built into Busness Copy. However, you can use another machine running Business Copy to kick of scheduled jobs that are configured on the SMA.

Hope this helps

Re: Business Copy EVA problem

Uwe Zessin — Thu, 08 Jul 2004 14:13:32 GMT

Jason,

I guess what Jerry wanted to say is: a 100 GigaBytes virtual disk in VRAID-1 takes up 200 GigaBytes of raw disk space. That leaves 50 GigaBytes of raw space.

A snapshot is currently using the same VRAID level like the parent virtual disk, so 50 GigaBytes of raw space allows for 25 GigaBytes of updates on the parent before the disk group is full. Please note that a disk group should never be filled to 100%.

Re: Business Copy EVA problem

Craig Rants — Thu, 08 Jul 2004 16:10:29 GMT

Could anyone provide some comments for the following questions about BC EVA?

- As I know, snapshot will exist in the same disk group with source Vdisk. If the total EVA space is 250G (one disk group), a 100G Vdisk with mirror was created. It means 200G of total EVA space used, and 50G is free. When we make a snap BCV, does this BCV can only use the available 50G space? so I can not use the "fully Allocated Snapshot". right?
Correct you will only be able to perform demand allocated, when it runs our of space however your copy will blow up...

- What is best practice for mirror and BCV?
I think this is probably subjective right now.

- If the source data does not change, is the size of the BCV vdiisk always zero?
If you change data on the snapshot disk or original disk, the change in allocation will grow by that amount changed.

- Where is the scheduling function within BC GUI?
Your best bet is to use the evmcl command and cron. i.e.

/opt/CPQevm/bin/evmcl eva001.domain.com run "SNAPSHOT_JOB"

GL,
Craig