Why do some VMs use SATA 0:1 for hard disk 1 and others use SCSI 0:1 ?!?

I have one VM running on a Mac Book Air, and is using the setting SCSI 0:1 for hard drive 1, while other VMs I have running on other machines all use SATA 0:1. Is there a reason behind this? Is SCSI used when the machine has an SSD installed? The reason I ask is that the VM with SCSI 0:1 runs like a 3-legged dog, while all my others on other hardware run great. I've gone through all the performance KBs and done everything mentioned within, but still no joy on the MBA. It's running Win 8.1 pro, and I don't see anything there out of the ordinary, except that harddrive reads/writes often spike up to 100% even though CPU is use is low, which led me to where I am today, wondering if the SCSI drive setting has anything to do with it. I sure remember them back in the day, and they were about as fast as a two-legged dog Well, thx!

 

hi,
have you migrated that vm? what if you manually change the interface to ide or sata?

 

Ha Marat! My VMs are migrated with almost major upgrade of VMWare and PD. They promise better performance / features, then you guys do, and I follow. Currently, PD is the host dejour. So yes, my VM has been migrated and I tried the other interfaces and the VM won't boot. So can we conclude that this VM may have performance issues based on HD I/O, or not? Thx!

 

No, basically, I don't think that SCSI has an influence on VM performance as we are talking here about virtual interfaces. The interesting thing is that Parallels Desktop doesn't use SCSI as the default interface. That means that VM wasn't created in Parallels Desktop and doesn't have built-in driver for sata/ide. I didn't understand your post above (about migration). If you migrated VM from a PC then better remove native PC drivers, If you migrated from Fusion, then remove VMware tools .

btw, what you mean by better performance/features?^^

 

Yes, I see. So that's not the reason that this particular VM does not run as good as it does under VMWare 7+, but perhaps because it was migrated from there might explain the problem (in lay terms). Interesting! On my migration path, it started way back in Version [Minus Some Number from Today] for both VMWare and PD. So in one case, I started out on VMWare with a Windows 7 VM, and PD comes out with a major release that sounds fantastic. Since I have a license for both products, I use the upgrade option to purchase that and use the migration tools provided to just convert to a new host program. Easy enough, cheap enough, let's see what happens. Oh, that VM runs a little bit better (less resources, better performance). At the same time, OSX is changing all the time, and sometimes as a developer, one or the another host programs breaks momentarily during the beta program. Ok, no problem, just migrate over to VMWare or PD, whatever the case, and continue to run this same VM. And like I said, that same VM has now come back home to roost inside of PD, in the form of Windows 8.1 Pro ready to go to Win 10. All is good, but just a tad slower than when it was in VMWare 7. So, hopefully that answers your questions, thx for listening

Ps. To clarify, I am a mac user who just creates Windows VMs to run both OSX and Windows at the same time, eliminating the need to ever own PC hardware, and this works out very well professionally

 

Thanks for reply! I am a little impressed that VM could go through this road =) going back to the issue I would recommend you uninstalling Fusion tools as it can lead to conflict with Parallels ones. If Mac Activity Monitor and Windows Task Manager counters are in the reasonable limits, then nothing else can be suggested, I'm afraid

 

Yes, that's always one of the first things that I do - is to remove all previous host tools. Performance is acceptable (PD 10), but when the VM first opens there is 100% R/W disk activity with no apparent CPU load or process impacting that. After a few minutes, that goes away. I've tried all the performance KBs, and still see this. So when I open the VM, I just take a break now before trying to use it. My only fear is that I am often in a classroom situation, and if the VM crashes, it becomes a distraction to have a 10-minute reboot time, essentially. So, now I am waiting for VMWare Fusion 8 to come out, and I will switch back to that to try and see if the problem gets corrected. If it does, that's where I will be in the future. See the cycle?