Physical Copy speed...

[Andy]

Long story behind this, but basically I have a 15TB thin provisioned virtual volume with about 8TB of actual data on it. We had an incident where I had to go back to a virtual copy of the data as quickly as possible, so I created a RW VC of the RO VC, exported and have been running on in for a couple of days.

Good news is that the users are happy and performance is good, but running from the VC makes me uncomfortable.

I decided to create a Physical copy of the RW VC and it is processing this copy task now, however, it is running really slow. At the current rate...it's going to take about 2 days to complete.

I can back this data up in 12 hours...restore I am guessing would be similar. I would have guessed that a process completely internal to the 3par would be at least as quick....not twice as slow.

I am just wondering if anyone has any experience with making Physical Copies. Is this normal? I know it is a lot of data....can't change that.

Also...is there another way to accomplish the same goal? I thought I could maybe promote the snap, but the option is greyed out and the documentation I've found is poor at best.

Thanks...Appreciate the help...

-Andy

[hdtvguy]

VC promotes and physical copies are slow, we complained early on and I forgot the numbers they gave us but it was around 11MB/sec and they did not expect much more than that. We have since made some changes to how we do certain copies and snaps to avoid using physical copies or promotes.

[Andy]

Well...maybe I should count my blessings as I am seeing 50MB/s. Still terrible. Seems with every turn I keep hitting a wall that ends up needing more than a day of downtime to fix this problem.

Thanks for the reply....anyone else have any suggestions?

-Andy

[Andy]

Ok....so after 1 hour it had copied 175MB. After 2 hours its has copied 3.2TB. So it has really picked up in speed. Very odd, but in a good way.

I'll post to the topic when it is complete, but seems like this might be a non-issue.

-Andy

[Andy]

I lied. Going to take about 48 hours to clone the 8TB volume. I thought it was going faster, but it was reporting progress based on the full size of the thin provisioned volume. So when it went fast it basically was not really moving data.

I can only hope that the resync is a MUCH faster process. Basically this great feature is not very great...especially with a large volume.

-Andy

[hdtvguy]

Depending on how often and the change rate the re-sync will be helpful since it only has to copy the changed blocks.

[Andy]

hdtvguy,
Thanks for the feedback...

Since you seem to have been down this road with copies/resyncs/promotes...and slightly unrelated to this thread...

I noticed in the IMC if you right click a VC, in the second section (starts with "Create Virtual Copy..) there is a "Promote Virtual Copy" pick. For me...it is always greyed out. 3par Users Guide talks about how to pick it from the menu, but I couldn't find anything that tells me the requirements in order to use the function. Any idea?

-Andy

[hdtvguy]

I'm guess it is greyed out because the base volume is exported? I believe the base voluem needs to be unexported and not a RC target.

[Andy]

Seems like a good guess. I'll experiment. Thanks for the suggestion.

Physical copy finished BTW. 7,100 GB took ~43 hours. Running resync now...with two days of delta on the volume.

-Andy

[Andy]

Resync ran very quickly (4 minutes). As long as promote does as well I think I am good.

I will still state that 3par taking 4x longer to copy the data than VMWare took seems really odd. Of course VMWare messed up with this large volume so...

I am feeling pretty confident that this will work.

-Andy