January 19, 2011 at 10:48 am
reuben.anderson (1/19/2011)
We're undergoing an enterprise consolidation and virtualisation project at the moment, and I currently have an external consultant proposing to replace our physical, clustered SQL Servers, with non-clustered VM's where the high availability is provided by VMWare HA.Does anyone have a view on this? Any serious pitfalls / constraints to take into consideration?
Thanks in advance.
Reuben
Rueben, ensure the VMotion network is on a dedicated, fast, secure network as VM configs including memory maps are passed unencrypted.
george sibbald (1/19/2011)
I believe that would mean you only have failover at the host level, not individual virtual servers.
a cluster configured for VMWare HA will provide failover to another ESX host in the HA cluster for any VM previously located on the failed ESX host
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
January 19, 2011 at 10:56 am
george sibbald (1/19/2011)
Perry,maybe it is taken as read but it should be mentioned another drive would be needed to install SQL application files to (i.e. the instance root directory) and this would not be a cluster resource.
C drive could be used for this but a drive for the purpose would be usual.
thanks for putting the article together. Any plans for an article on clustering other SQL components (mainly SSIS and SSRS)
Completely agree, generally you would have a D drive for application files although is this really absolutely necessary nowadays?
On SQL Server 2008 (not R2) there is a known issue with cluster installations whereby the shared components location on nodes you add to a clustered instance is ignored and goes straight to C: drive regardless. This is fixed in a later SP\CU so if slipstreaming the approprtiate fix should be fine. R2 doesn't have the issue.
It's preference i suppose, the idea was to keep things simple here and to the point without wittering on to much about best practices that most of us are aware of.
SSIS is not truely cluster aware and MS do issue warnings about configuring it so, SSRS is not cluster aware either. I am planning an article which uses Veritas Cluster Services, this product allows any Windows service to be configured as a cluster resource.
Glad you liked the article.
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
January 19, 2011 at 10:58 am
alen teplitsky (1/19/2011)
another plus is that windows clusters are a pain in the *** and changing minor things like IP's can break them.
changing the IP for what a clustered resource or for the Windows cluster itself?
alen teplitsky (1/19/2011)
no need for clusters on vmware
many organisations use both with great success, but i get what you're saying
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
January 19, 2011 at 11:05 am
Thanks Perry and Alex.
January 19, 2011 at 11:12 am
Perry Whittle (1/19/2011)
alen teplitsky (1/19/2011)
another plus is that windows clusters are a pain in the *** and changing minor things like IP's can break them.changing the IP for what a clustered resource or for the Windows cluster itself?
alen teplitsky (1/19/2011)
no need for clusters on vmwaremany organisations use both with great success, but i get what you're saying
i think it was for the cluster. did it a few years ago in testing and it broke the cluster. took me hours to figure it out by searching the registry. apparently when you change it in the cluster GUI it won't take in the registry or something like that. maybe it was the NIC IP's on the hosts. don't remember all the details.
and one other point, adding new drives to a cluster is another pain in the *****. you have to take the entire instance down to add a new drive
either way i think that SQL on vmware is OK if you run a lot of small databases with minimum I/O. but where i work we have some databases in the hundreds of GB where some queries select 5-10 GB of data. the only value with vmware in this case is to run it on a single instance/node just for the failover capability
January 19, 2011 at 11:21 am
What about patching? If you have to patch to install and you have a cluster, you can failover to one node and patch the other, then fail back and patch ther other node. The benefit is there's no loss of availability--while you're patching. I mention this as it might a reason to cluster usnig VMware. I suppose it depends on your requirements in terms of availability.
Any thoughts?
January 19, 2011 at 11:21 am
Would it be possible to get the complete tutorial for the VMWare Server\SQL Server 2008 install?
January 19, 2011 at 11:29 am
we have 3 clusters and it's always downtime in patching the SQL service packs. with windows patches you can do the inactive nodes at any time you want
January 19, 2011 at 11:33 am
alen teplitsky (1/19/2011)
and one other point, adding new drives to a cluster is another pain in the *****. you have to take the entire instance down to add a new drive
certainly not with Windows 2008 clusters and i can't say i ever have with Windows 2003 clusters either
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
January 19, 2011 at 11:35 am
we run sql 2005 and windows 2003
to add a new drive letter to an instance you have to take the instance down. i believe it's because you had to add it as a dependency to the SQL service.
on a stand alone SQL server you just add a letter
January 19, 2011 at 11:41 am
alen teplitsky (1/19/2011)
we run sql 2005 and windows 2003to add a new drive letter to an instance you have to take the instance down. i believe it's because you had to add it as a dependency to the SQL service.
on a stand alone SQL server you just add a letter
Thanks Alen. All of these are really good useability benefits of using SQL on VMWare... the main drawback seems to be a relatively small decrease in the availabilty as you will lose the ability to control the SQL instance independently from the OS. If you're going for 99.99% availability I don't think you can do it, but if you can tolerate a regular full outage for a maintenance window then the benefits are enormous.
January 19, 2011 at 11:47 am
we don't run SQL on vmware but if you were going to do it you would have to watch the I/O. even SQLCAT's testing showed that all the I/O goes through the hypervisor software and it can become a problem on busy databases.
there is also cost. by the time you buy the vmware licenses for everything it's a lot of money. compare it to clustering and you'll have to decide if it's right for you.
vmware originally had a killer ROI on solutions where someone would ask for a 1U server to run an app and it would take 10%CPU at most and a little RAM. Buying a few machines to run vmware was a lot cheaper than server creep since you have to buy a lot of accessories for servers. $3000 racks that do nothing but sit there and power. with SQL and new servers you can consolidate a lot of databases to very few servers. vmware/clustering is just for availability since there is no reason to run a server with only one or two small databases unless you have to for security/customer or some other reason. if your main concern is having current data at a DR location check out some of the disk backup software where it ships your backups to another unit
clustering will give you a better return on investment since you can run on both nodes at the same time. with vmware you have to have a server bought and paid for sit around and do nothing.
it's like backing up to disk vs tape and dedupe. every solution has costs, issues, problems and advantages and you have to decide if it's right for your environment
January 19, 2011 at 12:44 pm
alen teplitsky (1/19/2011)
i believe it's because you had to add it as a dependency to the SQL service.
yes, i'm with you now that's quite correct you add the disk as a dependency but you have to offline the service resource first. Shoould only take seconds and would normally be done in your maintenance window. For the protection clusters offer you will encounter the odd downside
-----------------------------------------------------------------------------------------------------------
"Ya can't make an omelette without breaking just a few eggs" 😉
January 19, 2011 at 6:15 pm
Perry
Does your tutorial cover setting up the cluster on VMware workstation 6.5? if it does please can I take a peek please.
Thanks
Gethyn
Gethyn Elliswww.gethynellis.com
January 19, 2011 at 8:53 pm
This concludes the article, as always I would urge you test and sanitise this process in an offline environment. This can be easily accomplished via the use of VMWare Server 2.0.x or if you have it available, VMWare ESX Server. A complete tutorial for the VMWare Server\SQL Server 2008 install is available on request (too large to post online).
Hi can you share this one VMWare Server\SQL Server 2008 install tutorial.
Viewing 15 posts - 16 through 30 (of 57 total)
You must be logged in to reply to this topic. Login to reply