I hate to say this, but probably no one knows why. I looked at the history and this method has always being like this.
The device ID 3 seems to be something reserved, probably for Xen tools (big guess here)? Also, regarding the limit; I could speculate two explanations for the limit. A developer did not get the full specs and decided to do whatever he/she wanted. Or, maybe, at the time of coding (long, long time ago) there was a hypervisor that limited (maybe still limits) the number of devices that could be plugged to a VM and the first developers decided to level everything by that spec. It may be worth checking with KVM, XenServer, Hyper-V, and VMware if they have such limitation on disks that can be attached to a VM. If they do not have, we could remove that, or at least externalize the limit in a parameter. On Wed, Feb 15, 2017 at 5:54 AM, Friðvin Logi Oddbjörnsson < frid...@greenqloud.com> wrote: > CloudStack is currently limiting the number of data volumes, that can be > attached to an instance, to 14. > More specifically, this limitation relates to the device ids that > CloudStack considers valid for data volumes. > In method VolumeApiServiceImpl.getDeviceId(long, Long), only device ids 1, > 2, and 4-15 are considered valid. > What I would like to know is: is there a reason for this limitation? (of > not going higher than device id 15) > > Note that the current number of attached data volumes is already being > checked against the maximum number of data volumes per instance, as > specified by the relevant hypervisor’s capabilities. > E.g. if the relevant hypervisor’s capabilities specify that it only > supports 6 data volumes per instance, CloudStack rejects attaching a > seventh data volume. > > > Friðvin Logi Oddbjörnsson > > Senior Developer > > Tel: (+354) 415 0200 | frid...@greenqloud.com <jaros...@greenqloud.com> > > Mobile: (+354) 696 6528 | PGP Key: 57CA1B00 > <https://sks-keyservers.net/pks/lookup?op=vindex&search= > frid...@greenqloud.com> > > Twitter: @greenqloud <https://twitter.com/greenqloud> | @qstackcloud > <https://twitter.com/qstackcloud> > > www.greenqloud.com | www.qstack.com > > [image: qstack_blue_landscape_byqreenqloud-01.png] > -- Rafael Weingärtner
