HPE Storage Users Group
https://3parug.com/

3PAR Remote Copy triggered a full sync for some volumes
https://3parug.com/viewtopic.php?f=18&t=2845		 Page 1 of 1
Author:  bihag [ Wed Apr 04, 2018 3:28 am ]
Post subject:  3PAR Remote Copy triggered a full sync for some volumes
I am on 3PAR 8200 with OS: 3.3.1.269 (MU1)+P07,P15,P21,P24. I use periodic async remote copy over RCIP to replicate 12 volumes to a DR site located ~ 500 KM away through 2 x 8 Mbps P2P links. I have SilverPeak VRX-2 to accelerate remote copy traffic. Daily we replicate ~ 230 GB on this setup.

Few days back, I noticed below error which triggered a full sync of 3 volumes aggregating to 7 TB !
"Remote Copy Volume 438(prd.ltcadc1.project3.vv) Degraded (Remote Copy Volume Volume Unsynced - primary periodic iteration doesn't match secondary {0xb})"

Had a nightmare to recover and bring it back to normal operations. The case with HPE Support is with Labs and under investigation. They have asked to apply P25 to both systems. And they suspect links are an issue. But nothing specific so far.

Any ideas on how to stop recurrence of such behaviour ?
Author:  MammaGutt [ Wed Apr 04, 2018 12:52 pm ]
Post subject:  Re: 3PAR Remote Copy triggered a full sync for some volumes
To my understanding, any form of WAN accelerators or optimizers aren't really supported with RC. Could be that this is your problem.

Also, 2x8Mbit links for 230GB per day isn't a lot to go on. That would give me 2MB/s, which is 7.2GB per hour or 172GB per day. If you need to replicate 230GB per day it would seem to me that "your pipes aren't big enough". When that happens you will at some point end up with the remote copy group requiring a full resync.

Are you seeing any messages like "periodic sync took more than sync period" or something like that?

If you see that and if possible, you could try to increase your sync intervals to a higher period to see if you get less changed data that needs to be replicated per minute.
Author:  bihag [ Wed Apr 04, 2018 10:33 pm ]
Post subject:  Re: 3PAR Remote Copy triggered a full sync for some volumes
Please refer below links which confirm compatible use remote copy with SilverPeak:

https://www.silver-peak.com/applications/hp-3par
https://www.silver-peak.com/solutions/r ... celeration

I get around 70-80 % compression with SilverPeak, so the 230 GB actually becomes 50-70 GB when put on WAN. Please refer attached snap where 258 GB data is compressed to 63 GB !
Attachment:
File comment: SilverPeak compression for 3PAR remote copy
SP.JPG
SP.JPG [ 31.7 KiB | Viewed 13138 times ]


With this the RPO remains to 2-3 hours which is much below the business commitment.

Yes, I do see those warnings "periodic sync took more than sync period", but I understand that the only impact of these in periodic async remote copy is increase in RPO.

I am planning to increase the period to a suitable value and see if this works. In any case I would need to confirm that this would stop any recurrence of full sync.
Author:  MammaGutt [ Thu Apr 05, 2018 12:04 am ]
Post subject:  Re: 3PAR Remote Copy triggered a full sync for some volumes
All I see on those links are SilverPeak marketing and not a single word about any partnership or that the solution is any way supported by HPE. You could try and log a case with SilverPeak and see how far that might get you.

I'm just going to ask..... Do you drive around in a car with a christmas tree in the dashboard? (ie all error lights are flashing) You are getting a clear indication that your replication links aren't good enough for your current setup while ignoring to do anything about it.

Your RPO means each repliction sync will take at least 1 hour to complete. What is your current setup and what is the business requirement? Seems like the good idea is to set your interval to 1/2 of your business requirement so that when you are not able to keep the requirement you actually get an error. Today it seems that you're always getting an error and you need to manually check and verify multiple times per day that you are within the RPO requirement. When the links are no longer able to substain the business requiremenr you have a business case for upgrading them.
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/