> From: Vishvananda Ishaya [mailto:vishvana...@gmail.com] > Sent: Tuesday, March 18, 2014 2:28 AM > To: OpenStack Development Mailing List (not for usage questions) > Subject: Re: [openstack-dev] [nova][cinder] non-persistent storage(after > stopping VM, data will be rollback automatically), do you think we shoud > introduce this feature? > > > On Mar 17, 2014, at 4:34 AM, Yuzhou (C) <vitas.yuz...@huawei.com> wrote: > > > Hi Duncan Thomas, > > > > Maybe the statement about approval process is not very exact. In fact in > my mail, I mean: > > In the enterprise private cloud, if beyond the quota, you want to create a > > new > VM ,that needs to wait for approval process. > > > > > > @stackers, > > > > I think the following two use cases show why non-persistent disk is useful: > > > > 1.Non-persistent VDI: > > When users access a non-persistent desktop, none of their settings or > data is saved once they log out. At the end of a session, > > the desktop reverts back to its original state and the user receives a > > fresh > image the next time he logs in. > > 1). Image manageability, Since non-persistent desktops are built from a > master image, it's easier for administrators to patch and update the image, > back it up quickly and deploy company-wide applications to all end users. > > 2). Greater security, Users can't alter desktop settings or install > > their own > applications, making the image more secure. > > 3). Less storage. > > > > 2.As the use case mentioned several days ago by zhangleiqiang: > > > > "Let's take a virtual machine which hosts a web service, but it is > > primarily > a read-only web site with content that rarely changes. This VM has three > disks. > Disk 1 contains the Guest OS and web application (e.g. Apache). Disk 2 > contains the web pages for the web site. Disk 3 contains all the logging > activity. > > In this case, disk 1 (OS & app) are dependent (default) settings and > is backed up nightly. Disk 2 is independent non-persistent (not backed up, and > any changes to these pages will be discarded). Disk 3 is independent > persistent (not backed up, but any changes are persisted to the disk). > > If updates are needed to the web site's pages, disk 2 must be > taken out of independent non-persistent mode temporarily to allow the > changes to be made. > > Now let's say that this site gets hacked, and the pages are > doctored with something which is not very nice. A simple reboot of this host > will > discard the changes made to the web pages on disk 2, but will persist > the > logs on disk 3 so that a root cause analysis can be carried out." > > > > Hope to get more suggestions about non-persistent disk! > > > Making the disk rollback on reboot seems like an unexpected side-effect we > should avoid. Rolling back the system to a known state is a useful feature, > but > this should be an explicit api command, not a side-effect of rebooting the > machine, IMHO.
I think there is some misunderstanding about non-persistent disk, the non-persistent disk will only rollback if the instance is shutdown and start again, and will persistent the data if it is soft-reboot. Non-persistent disk does have use cases. Using explicit API command can achieve it, but I think there will be some work need to be done before booting the instance or after shutdown the instance, including: 1. For cinder volume, create a snapshot; For libvirt ephemeral image backend, create new image 2.Update attached volume info for instance 3.Delete the cinder snapshot and libvirt ephemeral image, and update volume/image info for instance again These works can be done by users manually or by some "Upper system" ? Or non-persistent can be set as a metadata/property of volume/image, and handled by Nova? > Vish > > > > > Thanks. > > > > Zhou Yu > > > > > > > > > >> -----Original Message----- > >> From: Duncan Thomas [mailto:duncan.tho...@gmail.com] > >> Sent: Saturday, March 15, 2014 12:56 AM > >> To: OpenStack Development Mailing List (not for usage questions) > >> Subject: Re: [openstack-dev] [nova][cinder] non-persistent > >> storage(after stopping VM, data will be rollback automatically), do > >> you think we shoud introduce this feature? > >> > >> On 7 March 2014 08:17, Yuzhou (C) <vitas.yuz...@huawei.com> wrote: > >>> First, generally, in public or private cloud, the end users > >>> of VMs > >> have no right to create new VMs directly. > >>> If someone want to create new VMs, he or she need to wait for > >>> approval > >> process. > >>> Then, the administrator Of cloud create a new VM to applicant. So > >>> the > >> workflow that you suggested is not convenient. > >> > >> This approval process & admin action is the exact opposite to what > >> cloud is all about. I'd suggest that anybody using such a process has > >> little understanding of cloud and should be educated, not weird > >> interfaces added to nova to support a broken premise. The cloud /is > >> different/ from traditional IT, that is its strength, and we should > >> be wary of undermining that to allow old-style thinking to continue. > >> > >> _______________________________________________ > >> OpenStack-dev mailing list > >> OpenStackfirstname.lastname@example.org > >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > > _______________________________________________ > > OpenStack-dev mailing list > > OpenStackemail@example.com > > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev _______________________________________________ OpenStack-dev mailing list OpenStackfirstname.lastname@example.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev