+rajesh ----- Original Message ----- > From: "M S Vishwanath Bhat" <msvbhat@xxxxxxxxx> > To: "Vijay Bellur" <vbellur@xxxxxxxxxx> > Cc: "Lalatendu Mohanty" <lmohanty@xxxxxxxxxx>, "Avra Sengupta" <asengupt@xxxxxxxxxx>, "Raghavendra Bhat" > <rabhat@xxxxxxxxxx>, "Gluster Devel" <gluster-devel@xxxxxxxxxxx>, "Rahul Hinduja" <rhinduja@xxxxxxxxxx>, "Seema > Naik" <senaik@xxxxxxxxxx> > Sent: Tuesday, June 3, 2014 1:02:08 AM > Subject: Re: autodelete in snapshots > > On 2 June 2014 20:22, Vijay Bellur <vbellur@xxxxxxxxxx> wrote: > > > On 04/23/2014 05:50 AM, Vijay Bellur wrote: > > > >> On 04/20/2014 11:42 PM, Lalatendu Mohanty wrote: > >> > >>> On 04/16/2014 11:39 AM, Avra Sengupta wrote: > >>> > >>>> The whole purpose of introducing the soft-limit is, that at any point > >>>> of time the number of > >>>> snaps should not exceed the hard limit. If we trigger auto-delete on > >>>> hitting hard-limit, then > >>>> the purpose itself is lost, because at that point we would be taking a > >>>> snap, making the limit > >>>> hard-limit + 1, and then triggering auto-delete, which violates the > >>>> sanctity of the hard-limit. > >>>> Also what happens when we are at hard-limit + 1, and another snap is > >>>> issued, while auto-delete > >>>> is yet to process the first delete. At that point we end up at > >>>> hard-limit + 1. Also what happens > >>>> if for a particular snap the auto-delete fails. > >>>> > >>>> We should see the hard-limit, as something set by the admin keeping in > >>>> mind the resource consumption > >>>> and at no-point should we cross this limit, come what may. If we hit > >>>> this limit, the create command > >>>> should fail asking the user to delete snaps using the "snapshot > >>>> delete" command. > >>>> > >>>> The two options Raghavendra mentioned are applicable for the > >>>> soft-limit only, in which cases on > >>>> hitting the soft-limit > >>>> > >>>> 1. Trigger auto-delete > >>>> > >>>> or > >>>> > >>>> 2. Log a warning-message, for the user saying the number of snaps is > >>>> exceeding the snap-limit and > >>>> display the number of available snaps > >>>> > >>>> Now which of these should happen also depends on the user, because the > >>>> auto-delete option > >>>> is configurable. > >>>> > >>>> So if the auto-delete option is set as true, auto-delete should be > >>>> triggered and the above message > >>>> should also be logged. > >>>> > >>>> But if the option is set as false, only the message should be logged. > >>>> > >>>> This is the behaviour as designed. Adding Rahul, and Seema in the > >>>> mail, to reflect upon the > >>>> behaviour as well. > >>>> > >>>> Regards, > >>>> Avra > >>>> > >>> > >>> This sounds correct. However we need to make sure that the usage or > >>> documentation around this should be good enough , so that users > >>> understand the each of the limits correctly. > >>> > >>> > >> It might be better to avoid the usage of the term "soft-limit". > >> soft-limit as used in quota and other places generally has an alerting > >> connotation. Something like "auto-deletion-limit" might be better. > >> > >> > > I still see references to "soft-limit" and auto deletion seems to get > > triggered upon reaching soft-limit. > > > > Why is the ability to auto delete not configurable? It does seem pretty > > nasty to go about deleting snapshots without obtaining explicit consent > > from the user. > > > > I agree with Vijay here. It's not good to delete a snap (even though it is > oldest) without the explicit consent from user. > > FYI It took me more than 2 weeks to figure out that my snaps were getting > autodeleted after reaching "soft-limit". For all I know I had not done > anything and my snap restore were failing. > > I propose to remove the terms "soft" and "hard" limit. I believe there > should be a limit (just "limit") after which all snapshot creates should > fail with proper error messages. And there can be a water-mark after which > user should get warning messages. So below is my proposal. > > *auto-delete + snap-limit: *If the snap-limit is set to *n*, next snap > create (n+1th) will succeed *only if* *if auto-delete is set to on/true/1* > and oldest snap will get deleted automatically. If autodelete is set to > off/false/0 , (n+1)th snap create will fail with proper error message from > gluster CLI command. But again by default autodelete should be off. > > *snap-water-mark*: This should come in picture only if autodelete is turned > off. It should not have any meaning if auto-delete is turned ON. Basically > it's usage is to give the user warning that limit almost being reached and > it is time for admin to decide which snaps should be deleted (or which > should be kept) > > *my two cents* > > -MS > > > > > > Cheers, > > > > Vijay > > > > _______________________________________________ > > Gluster-devel mailing list > > Gluster-devel@xxxxxxxxxxx > > http://supercolony.gluster.org/mailman/listinfo/gluster-devel > > > _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://supercolony.gluster.org/mailman/listinfo/gluster-devel
