Leverage the Oracle Database Appliance Virtualized Platform

In my opinion, one of the best things to happen to Oracle Database Appliance recently was the availability of virtualization on the system. The virtualized Oracle Database Appliance (or "Oracle Database Appliance Virtualized Platorm" as it is officially called) allows you to run multiple virtual machines, hosting different tiers of your system architecture all within a single Oracle Database Appliance. And users love it! This is a major development for those looking for drastic cost reductions in managing their traditional multi-tier systems or even consolidating many systems into one, etc. Now you can have one single platform, that is already extremely easy to setup, operate, and manage, and host many virtual servers, deploying everything from your database to application logic tier to the web-tier and other supporting systems such as a load balancer, security server, etc. all in a single environment. Some ISVs are already looking for building and selling ready-to-go complete systems for their customers with everything inside one Oracle Database Appliance. 

The Oracle Database Appliance Virtualized Platform can be used with Oracle Appliance Manager (OAK) 2.5 and above for V1 hardware and with OAK 2.5.5 and above with Oracle Database Appliance X3-2 hardware. If you are on the non-virtualized deployment of your Oracle Database Appliance (and all new systems are currently  shipped from the factory with the non-virtualized ISO image), then you must re-image the server with the Oracle Database Appliance Virtualized Platform ISO image. Once you have re-imaged the servers with the virtualized platform ISO image, Oracle Appliance Manager lets you deploy a special virtual machine or domain called (ODA_BASE domain) to host all your databases. You allocate CPU and memory to this ODA_BASE domain as per your need (and available database licenses). Dedicated access to shared storage is provided to this domain by design (bypassing any negative performance impact of virtualization that it would otherwise incur) using the PCI pass through technique. The rest of the server capacity is available for deploying additional virtual machines for your application and web tiers and for other purposes.

You can check out the Oracle Database Appliance Getting Started Guide for more information. Also, the updated Oracle Database Appliance Setup Poster provides the details on setting up the Virtualized Platform on the Oracle Database Appliance X3-2 system. Virtualization for real!
Comments:

Hi,
Is really PCI Passthrough in action in terms of providing shared storage to ODA Base VMs? Isn't communication channel between front- and backend Xen drivers used here? As far as I know it has nothing to do with passtrough.

[root@dom11 ~]# lsmod |grep xen
xen_netfront 16356 0
xen_blkfront 13602 7
[root@dom01 ~]# lsmod |grep back
xen_blkback 22431 0 [permanent]
xen_netback 27587 0 [permanent]

On the other hand...

[root@dom1 ~]# lspci |grep -i scsi
00:04.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)
00:05.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)

[root@oda01 ~]# lsmod |grep pciback
xen_pciback 50967 0

I'm kind of confused here. By what means is access to shared storage really provided?? I'd be thankful for explanation.
Best regards.
Jacek

Posted by Jacek on June 18, 2013 at 01:32 AM PDT #

Hi Jecek,

Yes, PCI passthrough is used to provide direct access to shared storage from the ODA_BASE (also known as DOM1) domain.

Please see below. The PCI devices are hidden in the Dom0 domain as follows.

[root@dom0]# lspci |grep LSI
30:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)
40:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)
50:00.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)

[root@dom0]# grep xen-pciback /etc/modprobe.conf
options xen-pciback hide=(30:00.0)(40:00.0)

These devices are made available directly to the ODA_BASE (Dom1) domain through the vm.cfg file.

[root@dom0]# grep -i pci /OVS/Repositories/odabaseRepo/VirtualMachines/oakDom1/vm.cfg
pci = ['30:00.0@15', '40:00.0@16']

[root@dom1 ~]# lspci |grep -i scsi
00:15.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)
00:16.0 Serial Attached SCSI controller: LSI Logic / Symbios Logic SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] (rev 03)

[root@dom1 ~]# lsmod |grep xen
xen_netfront 16356 0
xen_blkfront 13602 7
[root@dom1 ~]#

Hope this clarifies.

Regards, Ravi

Posted by Ravi Sharma on June 24, 2013 at 10:34 AM PDT #

Hello Ravi,
Thanks a lot for the explanation. The part with modprobe.conf and vm.cfg makes the things clear for me.

Partly, I was confused by Xen documentation (http://wiki.xen.org/wiki/XenPVSCSI), specifically by last sentence: "Note that disks (any block device in dom0) can be passed to the Xen guest using the normal Xen blkback functionality, PVSCSI is not needed for that.".

Just one more question... if you don't mind.

I guess Dom1 is the equivalent for DomU. Thereby ODA Base, in terms of Xen's architecture, is just unprivileged domain like other user VM cloned from OVM templates. Is it correct?
Or maybe Dom1 term is introduced to distinguish, so to speak, partly privileged (e. g. shared storage access) ODA Base from unprivileged user VMs?
Thank you for your time.
Jacek

Posted by Jacek on June 24, 2013 at 11:32 AM PDT #

Hi Jecek,

No problem. Yes, Dom1 is basically a DomU. It is also called the ODA_BASE domain. It is more privileged (e.g., with PCI pass through capability, etc.) than the other DomUs. It is reserved for use as the database hosting domain.

Regards, Ravi

Posted by Ravi Sharma on June 24, 2013 at 11:54 AM PDT #

Hello, reading the ODA documentation, basically the Virtual Machine storage can be on local disks which may not be feasible given the limited capacity OR on the shared storage.

as I understand , the shared storage or repos as they are called are basically the ACFS file systems which are present in ODA_BASE. these repos are NFS exported to DOM 0 and made visible to VM's.

Question : if ODA_BASE goes down , as VM's have their storage on repos ie ACFS , the VM's will also suffer an outage?

Thanks
Sudhir

Posted by Sudhir on November 15, 2013 at 01:43 PM PST #

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The Oracle Database Appliance saves time and money by simplifying deployment, maintenance, and support of high-availability database solutions. This blog is dedicated to sharing updates about the Oracle Database Appliance from your product team.

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