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iSCSI is just a means to access "repositories" in Oracle VM. You can also use Fiber Channel, direct attach, NFS, and etc. Which method is faster depends on many different factors.
I don't understand question about "VBD files".
I assume VBD is "virtual block device". Accessing iSCSI direct will always be faster, but the difference will be nominal between iSCSI direct and a virtual disk on a iSCSI repository.
Thank you replying.
I also want to know about the way accessing to iSCSI Strage directly as physical disk.
VMware and KVM have the way accessing to physical disk directly.(by using vt-d or IOMMU. but OVM doesn't)
Does anybody have this kind of information about OVM?
You're right that IOMMU isn't supported in 3.1.1
Are you thinking this is a disadvantage for Oracle VM? Even using IOMMU you still have translations in place that cause overhead. IOMMU can increase CPU utilization under heavy loads.
Hi, Thank you for letting me know. I didn't know about that.
Maybe, Most of people don't understand exactly function.
When we see 'not support', We intend to think inferior product.
Anyway , Thank you.
I agree that it gives that impression. However, in any virtualized environment you're going to have some type of translation taking place between VM hosts and VM guests. IOMMU doesn't remove this. From what I've read.... IOMMU seems to be better with small transaction loads but under heavy loads it seems to take a hit. This is probably due in some measure to page table walks. I use direct attachments on all my Oracle database nodes. In fact that is the only supported method for Oracle RAC. (Virtual disks work but are not supported in a Production environment). I haven't seen any performance hits. I don't believe the lack of IOMMU has any impact in such a case or at least... very little.