Hi,

I have added an hyperswap volume copy to an existing 25TB volume.
The state of the remote copy is 'Inconsistent copying' and it is very slow.
I try to change the 'mirror sync rate' at the volume level but it seems it does not take this configuration setting for the initial sync.
Is there a way to speed up thing (will take 2 week!) and i see that the node to node links utilisation is very low (may be 5% max bandwith)

Thanks

-Stephane

Hi Stephane,

yes you can increase sync rate of hyperswap volumes. Default speed is 2 MB/s which indicates 50 in volume sync rate attribute value. Right click your hyperswap volume (not copies, just logical master volume) and choose modify sync rate and choose higher sync rate value. If you are using 8.3 or older code levels, this codes limited to up to 100 (means 64 MB/s) sync rate. 8.4 and later code levels support up to 2 GB/s.  

I believe the sync rate Nezih's post refers to is the rate that controls mirroring synchronisation and background formatting for thick volume copies.   For HyperSwap volumes, there are two configuration settings that affect the initial sync rate:

1. The local partnership settings.   The link bandwidth (in megabits per second) and the background copy rate (percentage) are used together to rate limit the total background copy between sites.  The initial sync of a new hyperswap volume copy comes under this background copy.

2. The per-volume background copy limit.   There is a system-level setting for the "relationship_bandwidth_limit", which is 25MB/s by default.   You can set this on the CLI using ('chsystem -relationshipbandwidthlimit <value_in_megabytes_per_second>').

If you're just looking to sync an individual volume then the per-volume setting is likely the limiting factor. 

You can change any of these settings non-disruptively, so it's fine to change them if desired for an initial sync, then return to your typical values for normal running.

Chris

Thanks Chris and T. Masteen.

Indeed the default setting for background_copy_rate or/and link_bandwidth_mbits was too low for the localpartnership:
- chpartnership -linkbandwidthmbits 8000 fs5200
- chpartnership -backgroundcopyrate 70 fs5200

I also increase the remove copy limit at the system level:
- chsystem -relationshipbandwidthlimit 1000

I may reduce the value once the initial sync id done.