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does the iscsi software adapter perform automatic rescans after a failuer to contact the initial datastore?

Posted on 2013-02-04
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Last Modified: 2013-02-19
was wondering if my iSCSI software adapter performs an automatic rescan, after the failure of the initial LUN it was connected to
example- ESXi host in an ESXi cluster is connected to a SAN via iSCSI.
the SAN goes down which disconnects the iSCSI connection
will the ESXi host perform automatic rescans of the drive until it comes back up?
if so, is there a default interval?
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Question by:jsctechy
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8 Comments
 
LVL 121
ID: 38851598
Yes, when you iSCSI SAN is back up and online, the iSCSI Software adaptor will re-connect and re-scan for new LUNs.

it regularly polls the iSCSI SAN, check Advanced settings under iSCSI Targets for values.
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by:jsctechy
ID: 38851741
thanks hanccocka
what would this be labeled as? RecoveryTimeout?
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LVL 121
ID: 38851998
I would not recommend changing any of the iSCSI values, unless your SAN vendor has specific values you need to use for your SAN.

With ESXi 5.0 the iSCSI login timeout is currently set 5 seconds, this means that after 5 seconds the ESXi host kills the iSCSI session if there is no response, and tries to login again immediately after.
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by:jsctechy
ID: 38852023
thanks Hanccocka
im not looking to change the value of this but here is the situation-
we are doing testing on some equipment at our datacenter, and when we simulate a SAN failure and bring it back up, we want to know how long after we bring the SAN up the iSCSI connection will come back to the ESXi host.
what we have been doing is a manual rescan of the vmhba but we want to know if we should be waiting a couple minutes longer for it to rescan on its own
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LVL 121
ID: 38852053
should be within a few seconds, off the SAN coming online.

we do not need to manually re-scan, if we take the SANs offline.

SAN failure is pull the power, wait 60 seconds, restart SAN!

ESXi should re-connect and datastores should be available, the moment the SAN is up and running.

we normally check with "ping".

what is the SAN?
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by:jsctechy
ID: 38852062
gotcha- im not 100% they are working that way
they are hp lefthands
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by:jsctechy
ID: 38852257
do you think its possible that this doesnt happen due to the type of SAN we have?
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LVL 121

Accepted Solution

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Andrew Hancock (VMware vExpert / EE MVE^2) earned 500 total points
ID: 38853036
Yes, I know the HP Lefthand SAN, the main cluster IP Address, should be available within seconds of it becoming online.
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