No issue with this behaviour - makes sense. However, the point I made about snapdelete being invoked when thinpool free space is threatened is a very real issue once you start using snaps. for 3.6 basing snap management on snapshot versions is fine, but I do think this needs to be extended to account for the thinpool freespace too in a subsequent release.
Maybe you already have it in plan? ----- Original Message ----- > From: "Rahul Hinduja" <rhind...@redhat.com> > To: "Avra Sengupta" <aseng...@redhat.com> > Cc: "Seema Naik" <sen...@redhat.com>, "gluster-devel" > <gluster-devel@nongnu.org> > Sent: Tuesday, 15 April, 2014 11:35:19 PM > Subject: Re: [Gluster-devel] autodelete in snapshots > ----- Original Message ----- > > From: "Avra Sengupta" <aseng...@redhat.com> > > To: "Lalatendu Mohanty" <lmoha...@redhat.com>, "Raghavendra Bhat" > > <rab...@redhat.com>, "gluster-devel" > > <gluster-devel@nongnu.org>, "Rahul Hinduja" <rhind...@redhat.com>, "Seema > > Naik" <sen...@redhat.com> > > Sent: Wednesday, April 16, 2014 11:39:11 AM > > Subject: Re: [Gluster-devel] autodelete in snapshots > > > > 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. > Agreed with Avra, the purpose of introducing soft limits and hard limits was > to restrict snap creation to reach limit+1 at any point in time. Any time > the limit reaches the hard limit the subsequent creation should fail. Once > the limit reaches the soft limit the auto-delete starts in background. Since > soft-limit is configurable option between 1-100, it really gives flexibility > to the user to start the auto-deletion based on his requirement it can be at > 1% or even 100% soft-limit. > If the auto-delete option is set to true than it should be triggered and > should log message based on user's input of soft-limit and if it is set to > false the auto-delete should only log message and snap creation fails when > it reaches the hard-limit. > Thanks, > Rahul > > > > Regards, > > Avra > > > > On 04/15/2014 07:18 PM, Lalatendu Mohanty wrote: > > > > > On 04/15/2014 07:05 PM, Raghavendra Bhat wrote: > > >> > > >> Hi, > > >> > > >> As of now, in snapshots there are 2 limits for the number of > > >> snapshots, hard-limit and soft-limit. Usually soft-limit is 90% of > > >> hard-limit by default (it can be changed also). Say the hard-limit is > > >> 50, then soft-limit by default will be 45. We are planning to do > > >> autodelete of the oldest snapshot upon reaching the limit. > > >> > > >> There are 2 options: > > >> > > >> 1) Start doing autodelete upon reaching the soft-limit. i.e If the > > >> hard limit is 50 and the number of the snapshots taken becomes 45, > > >> then for the next snapshot taken (i.e 46th snapshot), the oldest > > >> snapshot will be automatically deleted in the background. > > >> > > >> 2) Use soft-limit as a means to notify the admin about limit being > > >> reached (gf_log, syslog etc, or also a warning message shown for > > >> every snapshot taken after the soft limit is reached) and start doing > > >> autodelete after reaching the hard-limit i.e once 50 snapshots are > > >> reached, then when 51st snapshot is triggered, the oldest snapshot > > >> will be deleted in the background. > > >> > > >> Please provide feedback. > > > > > > I like the #2 option. If user has set something as hard-limit, it > > > should be treated as hard limit and soft-limit can be used as warning > > > mechanism. > > > > > >> > > >> NOTE: The auto-delete can be made configurable, which if turned off, > > >> snapshot create fails upon reaching the limit. > > >> > > >> Regards, > > >> Raghavendra Bhat > > >> > > >> _______________________________________________ > > >> Gluster-devel mailing list > > >> Gluster-devel@nongnu.org > > >> https://lists.nongnu.org/mailman/listinfo/gluster-devel > > > > > > > > > _______________________________________________ > > > Gluster-devel mailing list > > > Gluster-devel@nongnu.org > > > https://lists.nongnu.org/mailman/listinfo/gluster-devel > > > > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@nongnu.org > https://lists.nongnu.org/mailman/listinfo/gluster-devel
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