What is the data rate between a VM and the array?

[pepar]

I will be running JRiver in a Linux VM on an unassigned device (plugin) SSD.  At what speed does the VM read/write from/to the array? SATA III, which I'd guess, is limited by my WD REDs?

 

Jeff

[1812]

the virtual nic you are using with the vm determines speed to/from the array. if a para-virtualized 10gbe nic is used, then it should run as fast as the drive in the array you are writing/reading to it will allow, in theory. If using a virtual gigabit adapter, then the best you will see is gigabit speeds. 

 

Some vm's let you mount an unRaid share directly into the vm. That may be faster, but I don't know because I've never done it.

[pepar]

I have been mounting an unRAID share, or at least setting up the VM to do so, but have yet to be able to find it in the Linux installed in the VM.   

[DoeBoye]

I did some very quick testing last night:

1. Transfers From array To SSD-based Win10 VM seem to run between 40 and 70 MB/s. I would have thought this would be higher, but I have quite a hodge-podge of disks, so it might have been coming from an older, slower drive.
2. Transfers From Win10 VM (SSD) To different SSD Cache drive: 150 MB/s and up. Will need to use a larger data set to test more thoroughly. My test file was only a few hundred MBs. Funny enough, all my large files are stored in the array. I'll need to transfer some isos over to test larger files .

If there's interest, I could do a few more tests using larger data sets and disk shares instead of user shares to isolate the source drive.

 

Edited May 4, 2017 by DoeBoye

[pepar]

So, it looks to be a factor of the read/write speed of the slowest of the two involved in the transfer?

 

I was thinking that it would be that, up to the speed of the data bus, SATA or USB.

[DoeBoye]

59 minutes ago, pepar said:

So, it looks to be a factor of the read/write speed of the slowest of the two involved in the transfer?

 

When writing from an internal drive to the cache drive, read speed of source and write speed of destination are definitely the major factors. That said, there might be other stuff involved as well that I'm not aware of, as honestly, even my oldest drive should have faster read speeds than that...

 

[Edit] This is assuming, of course, that there is no bus bottleneck... obviously a ssd source transferring to a ssd cache on a PCI-based controller card is going to be limited by the 133MB/s bus speed limit of PCI, but that is an edge case, and frankly, a bit silly

 

Edited May 4, 2017 by DoeBoye