Comments for Adam's Tech Notes http://www.arkf.net/blog Fri, 18 May 2012 15:49:54 +0000 hourly 1 http://wordpress.org/?v=3.3.2 Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Adam http://www.arkf.net/blog/?p=355#comment-1522 Adam Fri, 18 May 2012 15:49:54 +0000 http://www.arkf.net/blog/?p=355#comment-1522 Yes, this is quite a common issue with vSphere, so much so that there are VMware KB's (eg: http://communities.vmware.com/docs/DOC-11987). Additionally, if you look at the VMware VDR, there are some fairly strict requirements for quiesced snapshots. I do a lot of VMware consulting and one that I come across fairly regularly is windows VM's using the Microsoft iSCSI adapter to attach additional LUN's internally within the VM. This is <u>not</u> supported and will cause the VMware VSS provider to fail, in turn causing your VM to fail it's quiesced snapshot. A work around for this is to use a Virtual RDM lun through VMware instead. These can be snapshot and are supported by VMware VSS. Yes, this is quite a common issue with vSphere, so much so that there are VMware KB’s (eg: http://communities.vmware.com/docs/DOC-11987). Additionally, if you look at the VMware VDR, there are some fairly strict requirements for quiesced snapshots. I do a lot of VMware consulting and one that I come across fairly regularly is windows VM’s using the Microsoft iSCSI adapter to attach additional LUN’s internally within the VM. This is not supported and will cause the VMware VSS provider to fail, in turn causing your VM to fail it’s quiesced snapshot. A work around for this is to use a Virtual RDM lun through VMware instead. These can be snapshot and are supported by VMware VSS.

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Mike G http://www.arkf.net/blog/?p=355#comment-1521 Mike G Fri, 18 May 2012 15:44:44 +0000 http://www.arkf.net/blog/?p=355#comment-1521 Just to close the loop on this, I found the cause of the excessive snapshots to be backup software quiescing. I tried with VDR and NetBackup, they both seemed to cause the problem. I disabled quiescing in NetBackup and have not lost connection to the ESX server for about 3 weeks. So in conclusion I believe something about that specific VM is not playing nice with snapshot quiescing. The only thing different about that VM is it is on a different VLAN and a different AD domain. Just to close the loop on this, I found the cause of the excessive snapshots to be backup software quiescing. I tried with VDR and NetBackup, they both seemed to cause the problem. I disabled quiescing in NetBackup and have not lost connection to the ESX server for about 3 weeks.
So in conclusion I believe something about that specific VM is not playing nice with snapshot quiescing. The only thing different about that VM is it is on a different VLAN and a different AD domain.

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Pete http://www.arkf.net/blog/?p=355#comment-1513 Pete Sat, 12 May 2012 14:25:12 +0000 http://www.arkf.net/blog/?p=355#comment-1513 This happened to me yesterday. Turned out there was a VM that had 200+ orphaned snapshots (didn't show up in the snapshot manager). I consolidated that VM, then re-added the host to the cluster, and all was good. As for what was creating the orphaned snapshots, I'm not entirely sure. I suspect VDR. This happened to me yesterday. Turned out there was a VM that had 200+ orphaned snapshots (didn’t show up in the snapshot manager). I consolidated that VM, then re-added the host to the cluster, and all was good.

As for what was creating the orphaned snapshots, I’m not entirely sure. I suspect VDR.

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Aaron http://www.arkf.net/blog/?p=355#comment-1500 Aaron Tue, 01 May 2012 00:34:07 +0000 http://www.arkf.net/blog/?p=355#comment-1500 Mike G's fix worked for me too. I had a VM with ~230 phantom snapshots. Thanks Mike! Mike G’s fix worked for me too. I had a VM with ~230 phantom snapshots. Thanks Mike!

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Mike G http://www.arkf.net/blog/?p=355#comment-1491 Mike G Wed, 25 Apr 2012 20:25:21 +0000 http://www.arkf.net/blog/?p=355#comment-1491 typo on above command should be: ls -l /vmfs/volumes/4*/*delta* | less typo on above command should be:
ls -l /vmfs/volumes/4*/*delta* | less

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by Mike G http://www.arkf.net/blog/?p=355#comment-1439 Mike G Tue, 24 Apr 2012 15:30:42 +0000 http://www.arkf.net/blog/?p=355#comment-1439 I had the same problem as you guys. I ended up calling tech support and this is how we got it resolved. 1st try bouncing services (this will not effect the still-running VMs) like this: -SSH in to the disconnected host -type: services.sh restart If this does not resolve, see if there is a group of failed backups by typing: ls -l /vmfs/volumes/4*/*deltea* | less If there are lots of entries this is probably the problem (for us there were 200+ for one VM) we were then able to fix the problem by: -create a snapshot of the problem VM using the GUI Snapshot tool -open snapshot manager and 'delete all' -Note it took about 2 hours to complete deleting all snapshots . You might think it is hung but it is not. If you are not sure, here is an article how to monitor a snapshot commit / delete VMW KB 1007566. Hope this Helps I had the same problem as you guys. I ended up calling tech support and this is how we got it resolved.
1st try bouncing services (this will not effect the still-running VMs) like this:
-SSH in to the disconnected host
-type: services.sh restart

If this does not resolve, see if there is a group of failed backups by typing:
ls -l /vmfs/volumes/4*/*deltea* | less
If there are lots of entries this is probably the problem (for us there were 200+ for one VM)
we were then able to fix the problem by:
-create a snapshot of the problem VM using the GUI Snapshot tool
-open snapshot manager and ‘delete all’
-Note it took about 2 hours to complete deleting all snapshots . You might think it is hung but it is not. If you are not sure, here is an article how to monitor a snapshot commit / delete VMW KB 1007566.

Hope this Helps

]]> Comment on vCenter Error: Cannot synchronize host. A general system error occurred. by vinzcenzo http://www.arkf.net/blog/?p=355#comment-1222 vinzcenzo Fri, 20 Apr 2012 12:32:52 +0000 http://www.arkf.net/blog/?p=355#comment-1222 Hi There, I Have the same issue and like Mike Payne, I'm still not able to reconnect the host to the vCenter. Any suggestion? Bests Vincent Hi There,

I Have the same issue and like Mike Payne, I’m still not able to reconnect the host to the vCenter.

Any suggestion?

Bests

Vincent

]]> Comment on Convert Linux Software RAID1 to RAID5 by nael http://www.arkf.net/blog/?p=47#comment-928 nael Fri, 13 Apr 2012 19:44:53 +0000 http://arkf.net/blog/?p=47#comment-928 Hi, Nice article and comments. Thanks!! BTW, I found this because I want to convert a RAID-0 to RAID-5... I found safer the Destructor solution, but will not work in my case. I think the original should work (can someone confirm this?), but it would be risky. As I don't have enough space for backup everything (just a half), I think the better solution would be to move the files from the actual RAID0 to the new disk for the RAID5 and some free space in the system one.. Then build an empty RAID5 with two disks, and recopy there the distributed files, and once the new disk is free I add it to the RAID... Hi, Nice article and comments. Thanks!!

BTW, I found this because I want to convert a RAID-0 to RAID-5…
I found safer the Destructor solution, but will not work in my case. I think the original should work (can someone confirm this?), but it would be risky.

As I don’t have enough space for backup everything (just a half), I think the better solution would be to move the files from the actual RAID0 to the new disk for the RAID5 and some free space in the system one.. Then build an empty RAID5 with two disks, and recopy there the distributed files, and once the new disk is free I add it to the RAID…

]]> Comment on Vyatta OpenVPN Site-to-Site from Behind NAT or Firewall by kk http://www.arkf.net/blog/?p=231#comment-908 kk Fri, 13 Apr 2012 15:39:05 +0000 http://arkf.net/blog/?p=231#comment-908 Ok. That makes more sense. Ok. That makes more sense.

]]> Comment on Vyatta OpenVPN Site-to-Site from Behind NAT or Firewall by Adam http://www.arkf.net/blog/?p=231#comment-902 Adam Fri, 13 Apr 2012 13:33:21 +0000 http://arkf.net/blog/?p=231#comment-902 An OpenVPN site-to-site link is refered to as a point-to-point link. This is a special case where you are not really creating a network per se, instead you are simply assinging the remote "end point" of the link. With a point to point link, when you put packets into the start of the tunnel, the only place it can come out is the end of the tunnel, there are no other hosts IP's needed in this case. Because there is literally no-where else for the packet to go, a /32 is used. Now, if you were using an ethernet link instead of a Vyatta point-to-point link, the smallest network you could use is a /30 which has 2 hosts, a broadcast and a network address. An OpenVPN site-to-site link is refered to as a point-to-point link. This is a special case where you are not really creating a network per se, instead you are simply assinging the remote “end point” of the link. With a point to point link, when you put packets into the start of the tunnel, the only place it can come out is the end of the tunnel, there are no other hosts IP’s needed in this case. Because there is literally no-where else for the packet to go, a /32 is used.

Now, if you were using an ethernet link instead of a Vyatta point-to-point link, the smallest network you could use is a /30 which has 2 hosts, a broadcast and a network address.

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