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thanks for your reply, but i have a question about Corosync + Pacemaker.
Now I want to use Corosync + Pacemaker in iscsi target


iSCSI Active/Passive With Virtual IPs

Server1 accesses the two targets/GWs one at a time

through one or more Virtual IPs. The server1 use oracle.

If the active target goes down, corosync/pacemaker will

activate the passive target.

IPMI fencing, one of the most common types, takes a few seconds.

I feel that this time is too long,

Can it guarantee my business is not interrupted?

On 16/10/15 05:20 AM, Shilu wrote:

> When master is down, can the time of switching backup to master be

> shorter than a second?

Not safely, no.

In HA, if a node is declared dead, it needs to be fenced/stonith'ed before its services are recovered. Not doing this can lead to a split-brain. The process of fencing a node takes time; Exactly how much depends on the device or method you are using. IPMI fencing, one of the most common types, takes a few seconds.

Also, if you shorten the time it takes to declare a node dead, you increase the chance of having a node declared dead when it's not.

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