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3 Replies Last post: Aug 30, 2009 11:53 PM by Anton V Zhban…  

HA / FT - What happens if (one) host looses connection to SAN/LUN posted: Aug 29, 2009 3:13 AM

Click to view asp24's profile Enthusiast
asp24
103 posts since
Oct 11, 2006

I have a few hosts in a cluster running HA/DRS (and I have tested FT a few times).

A few days ago one of the hosts loose connection to the SAN. I tried to do a rescan, but it said another scan was in progress etc.. So I apparently have some vmware/san issues. The problem was that I had to reboot the host to make HA restart the VM's on a different host. Is it possible to protect against these kind of failures? Or do I have to create some sort of cron-script that check connectivity and run a reboot -f or something if storage fails? (remember, the SAN IS UP, but one host looses connectivity.

Re: HA / FT - What happens if (one) host looses connection to SAN/LUN

1. Aug 30, 2009 2:45 PM in response to: asp24
Click to view bulletprooffool's profile Master
bulletprooffo…
806 posts since
Apr 14, 2009
Hmmm,

HA is really aimed at resolving host isolation / network connectivity to the ESX host.
have a look at your HA configuration settings though as it is possible that your VMs are not set to start.
Also, your VMs need to have the VM Tools installed as this is used for the heartbeat checking on VMs,

FT should recover VMs that disappear though - did the affected VMs all have FT enabled?

have a look at :
http://www.vmware.com/pdf/vmware_ha_wp.pdf

Re: HA / FT - What happens if (one) host looses connection to SAN/LUN

2. Aug 30, 2009 3:05 PM in response to: bulletprooffo…
Click to view asp24's profile Enthusiast
asp24
103 posts since
Oct 11, 2006

The main problem is that the host is still online.

HA was on, but not FT. I know that it is possible to turn on VM monitoring, and that would reboot most of the servers (some have VERY little disk usage, so they will not crash as most will). But this will not guarantee that they restart on different hosts, will it? (I guess not)

I have not tried to provoke an error to the storage when using FT. Anyone knows what will happen if the primary FT VM loose storage?

Re: HA / FT - What happens if (one) host looses connection to SAN/LUN

3. Aug 30, 2009 11:53 PM in response to: asp24
Click to view Anton V Zhbankov's profile Champion
Anton V Zhban…
2,877 posts since
May 26, 2008
FT uses disk based failure detection with heartbeats, so if primary VM loses disk connection - FT will switch over to secondary.

---
VMware vExpert '2009
http://blog.vadmin.ru

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