Comments on: Virtualization Short Take #5 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/ The weblog of an IT pro specializing in virtualization, storage, and servers Thu, 18 Mar 2010 06:21:17 +0000 http://wordpress.org/?v=abc hourly 1 By: slowe http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/comment-page-1/#comment-43712 slowe Wed, 25 Feb 2009 21:38:26 +0000 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/#comment-43712 Berkut83, The later versions of vCenter Server and ESX have VM failure monitoring, where vCenter Server will monitor VMware Tools heartbeats, disk I/O, and network I/O to determine if the VM has failed, and to restart it if so desired. However, you are correct in that VMware HA will not protect against a corrupted system image. Berkut83,

The later versions of vCenter Server and ESX have VM failure monitoring, where vCenter Server will monitor VMware Tools heartbeats, disk I/O, and network I/O to determine if the VM has failed, and to restart it if so desired.

However, you are correct in that VMware HA will not protect against a corrupted system image.

]]> By: berkut83 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/comment-page-1/#comment-43708 berkut83 Wed, 25 Feb 2009 13:42:51 +0000 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/#comment-43708 I'm not still well informed about vmware ha, but MSCS i think that has still an advantage over vmware ha It can recover a situation where the operating system is getting corrupted because in effect you have 2 separated operating systems, not just one switched between 2 esx servers. So, assume that on the first node you install a service pack which makes the node crashing.....the cluster mscs will fail over the second node On the countrary, what about vmware ha? if i am not wrong you don't have an operating system health monitoring If I am wrong, correct me I’m not still well informed about vmware ha, but MSCS i think that has still an advantage over vmware ha

It can recover a situation where the operating system is getting corrupted because in effect you have 2 separated operating systems, not just one switched between 2 esx servers.

So, assume that on the first node you install a service pack which makes the node crashing…..the cluster mscs will fail over the second node

On the countrary, what about vmware ha? if i am not wrong you don’t have an operating system health monitoring

If I am wrong, correct me

]]> By: Stephen Foskett http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/comment-page-1/#comment-36972 Stephen Foskett Mon, 07 Apr 2008 18:51:22 +0000 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/#comment-36972 I found lots of great NFS for VMware content in this NetApp whitepaper: http://www.netapp.com/us/library/technical-reports/tr_3428.html I found lots of great NFS for VMware content in this NetApp whitepaper:
http://www.netapp.com/us/library/technical-reports/tr_3428.html

]]> By: slowe http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/comment-page-1/#comment-36951 slowe Mon, 07 Apr 2008 00:22:54 +0000 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/#comment-36951 Massimo, I guess my view of the "statefulness" of MSCS is that you at least aren't, from all appearances, tossing the file system and all applications to the wind, hoping that transaction logs and file system checks will keep you safe. I agree that an MSCS cluster is not totally and completely stateful, but it is certainly more stateful than VMware HA. Not that there's anything wrong with HA, per se; there's just something about me that is uncomfortable with a guest OS rebooting, having to replay file system transactions, replaying application transactions, etc. I've seen, as I'm sure we all have, corrupted databases as a result. For that reason, I'm looking forward to Continuous Availability, which I agree will bring a new level of statefulness that MSCS cannot even begin to touch. Massimo,

I guess my view of the “statefulness” of MSCS is that you at least aren’t, from all appearances, tossing the file system and all applications to the wind, hoping that transaction logs and file system checks will keep you safe. I agree that an MSCS cluster is not totally and completely stateful, but it is certainly more stateful than VMware HA.

Not that there’s anything wrong with HA, per se; there’s just something about me that is uncomfortable with a guest OS rebooting, having to replay file system transactions, replaying application transactions, etc. I’ve seen, as I’m sure we all have, corrupted databases as a result.

For that reason, I’m looking forward to Continuous Availability, which I agree will bring a new level of statefulness that MSCS cannot even begin to touch.

]]> By: Massimo http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/comment-page-1/#comment-36939 Massimo Sun, 06 Apr 2008 10:08:33 +0000 http://blog.scottlowe.org/2008/04/04/virtualization-short-take-5/#comment-36939 Scott, I can't claim to be a cluster expert either but my understanding is that MSCS is not a stateful solution. If the application needs to be restarted on the other node of the cluster the last string of application transactions that are not yet committed to disk get lost (as it is the case of a vm that needs to restart on another host). The difference is that with MSCS you only restart the app on the other node while with VMware HA you have to restart the whole vm (OS+app). My understanding is that there is no difference in terms of stateful/stateless capabilities. In fact VMware Continuous Availability will bring a brand new level of HA into the game .. which is well above what MSCS can guarantee today. Massimo. Scott,

I can’t claim to be a cluster expert either but my understanding is that MSCS is not a stateful solution. If the application needs to be restarted on the other node of the cluster the last string of application transactions that are not yet committed to disk get lost (as it is the case of a vm that needs to restart on another host). The difference is that with MSCS you only restart the app on the other node while with VMware HA you have to restart the whole vm (OS+app). My understanding is that there is no difference in terms of stateful/stateless capabilities.

In fact VMware Continuous Availability will bring a brand new level of HA into the game .. which is well above what MSCS can guarantee today.

Massimo.

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