Hi LevinThank you, yes I leave IOPs empty. And the KVM host has SSDs in a hardware RAID 5 configuration, of which I am using local storage pool, yes. I will run fio test and also playing around with the controller cache settings to see what happens and provide feedback on this soon.
On 7/7/23 17:23, Levin Ng wrote:
HI Groete, Should you run a fio test on the VM and the KVM host to get a baseline first. SSD are tricky device, when it fill up the cache or nearly full, the performance will drop significantly, especially consumer grade SSD. There are option to limit IOPs in ACS offering setting, I believe you leave it empty, so it is no limit. When you talking about KVM uses SSDs, I think you are using Local Disk Pool right? If you have RAID controller underlying, try toggle the controller cache, SSD may perform vary on different disk controller cache setting. Controller type scsi, or virtio performance are similar, no need to worry about it. Of coz, in general, using RAW format and thick provisioning could get a best io performance result, but consume space and lack of snapshot capabliblity , so most the time it is not prefer go this path. Please gather more information first Regards, Levin On 7 Jul 2023 at 15:30 +0100, Granwille Strauss<[email protected]>, wrote:Hi Guys Does Cloudstack have a disk write speed limit somewhere in its setting? We have been transferring many files from remote servers to VM machines on our Cloudstack instance and we recently noticed that the VM write speeds are all limited to about 5-8 MB/s. But the underlying hardware of the KVM uses SSDs capable of write speeds of 300 - 600 MB/s. My disk offering on my current vms are set to "No Disk Cache" with thin provisioning, could this be the reason? I understand that "Write Back Disk Cach" has better write speeds. Also I have VMs set as virtio for its disk controller. What could I be missing in this case? -- Regards / Groete Granwille Strauss // Senior Systems Admin e:[email protected] m: +264 81 323 1260 w:www.namhost.com Namhost Internet Services (Pty) Ltd, 24 Black Eagle Rd, Hermanus, 7210, RSA The content of this message is confidential. If you have received it by mistake, please inform us by email reply and then delete the message. It is forbidden to copy, forward, or in any way reveal the contents of this message to anyone without our explicit consent. The integrity and security of this email cannot be guaranteed over the Internet. Therefore, the sender will not be held liable for any damage caused by the message. For our full privacy policy and disclaimers, please go tohttps://www.namhost.com/privacy-policy
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