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What is the best way to solve snapshot 'Backlog Warning' issues?

Rafael Fonseca
Occasional Advisor

What is the best way to solve snapshot 'Backlog Warning' issues?

We've got a two-shelf physical P4500 G2 snapshotting to a remote VSA on another datacenter that keeps alerting me to schedule backlogs happening on some of the most accessed volumes.

I tried decreasing the number of snapshots by setting them further apart, but the problem still happens. I also tried setting the snapshots for overnight, but then this morning I got a lot of 'Snapshot Failed' messages stating that the management group was overloaded.

What is the best way to resolve backlogs while still doing snapshots regularly?
4 REPLIES
Dan Harker
Occasional Contributor

Re: What is the best way to solve snapshot 'Backlog Warning' issues?

Hi,

Did you manage to resolve this?

 

Regards

Dan

oikjn
Honored Contributor

Re: What is the best way to solve snapshot 'Backlog Warning' issues?

it sounds like you might have a bandwith limitation problem.

 

What is your connection link speed?   If your change rate is greater than that speed, it doesn't matter how quickly or slowly you set your snapshots, you will never be able to keep up.

Dan Harker
Occasional Contributor

Re: What is the best way to solve snapshot 'Backlog Warning' issues?

We have a 1Gb link between sites, don't think it's bandwidth their as the remote copy completes with enough time. For example a 4 hour schedule copies across with 30mins or less. Its something todo with resyncing on the remote side that's causing it, just not sure what at the moment. Regards Dan
oikjn
Honored Contributor

Re: What is the best way to solve snapshot 'Backlog Warning' issues?

its either your link speed, your hdd speed or your CPUs...  if your link is actually supposed to be 1Gb, then its most likely time to start looking at the CMC perfmon to see what is spiking and seems to be maxing out....

 

My cheap VSAs with back ends of only a pair of 1TB HDDs in raid1 can do 100MB/s,. but there is no other load on those VSAs when that is going on.