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Mirrorview/A over iscsi
I have 2 clariions CX4-120 , 1 at live site and the other at disaster recovery site , Mirrorview/A is enabled , There are 11 LUNS to be replicated to disaster recovery site through iscsi over a 2mb/s link , 6 luns are 1TB and the other 4 are 2 TB , The problem is that it is taking too long to synchronise , On fracturing some luns leaving 2 to do initial synchronise , it moves 1% after 2 days , What could be causing this slowness
Jsang2
16 Posts
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June 23rd, 2011 07:00
Forgot to mention that latency between the iscsi ports on the 2 storage nodes is very high about 1000ms and keeps going up
Trace root has double hops
yassine2
64 Posts
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June 23rd, 2011 07:00
have you tested the line with ftp for example?
have you concistency groups?
have the initial synchronisation been successfull?
kelleg
4.5K Posts
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June 23rd, 2011 11:00
Have your network provider determine the bandwidth, not what it is suppose to be, but what is measured. 1000ms latency is pretty bad. Also, a 2mb (bit or byte) is slow - that sounds like a T1 connection speed 1.5Mbit /s (150KBytes/s).
glen
Jsang2
16 Posts
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June 24th, 2011 08:00
Ftp is blocked on the network
At the moment I don't have any Consistency group
1 luns is running the initial synchronisation
Are there any tools from EMC that can be used to measure bandwidth utilization ?
DanJost
190 Posts
1
June 27th, 2011 07:00
When I implemented MV/A, EMC came out and tested the circuit. I'm assuming you/they never did this? I am running MV/A over the iSCSI ports without any problems but my WAN circuit is 100Mbits. When they tested it they "certified" up to 85Mbits and did the feasibility calculations based on that. The result was that we could MV/A the entire storage system on a fairly short time schedule. Your circuit seems awfully slow for the amount of data you are trying to synchronize. You will get high latency when the circuit is essentially 100% full which is probably happening on the initial sync so unless you have other network issues a high latency might not be the problem only a symptom of not enough bandwidth.
You'll also run into problems if you are a frame-relay like guaranteed bandwidth setup with best-effort burst. I don't see many circuits like this anymore, though...but if you do you have the potential for a lot of discards and retransmits.
Dan
Jsang2
16 Posts
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July 15th, 2011 00:00
Thank you all for the answers given, The network was identified to be cause of the problem , Network link was upgraded to 3 MB/s and seems faster now however the Lun which was doing the initial synch but the the time didn't change on the Lun and the image state is showing (T) synchronizing
Last started is showng the date when the remote mirrorview/A was created and Last ended is showing N/A
The other question is the incremental copy seems to restart any time the link goes down , Is there any setting I missed out ?
christopher_ime
2K Posts
1
July 23rd, 2011 20:00
>> The other question is the incremental copy seems to restart any time the link goes down , Is there any setting I missed out ?
Please refer to the following post which will explain what you are seeing.
https://community.emc.com/thread/123610