On 3 June 2014 01:02, M S Vishwanath Bhat <msvbhat@xxxxxxxxx> wrote:
On 2 June 2014 20:22, Vijay Bellur <vbellur@xxxxxxxxxx> wrote:
I still see references to "soft-limit" and auto deletion seems to get triggered upon reaching soft-limit.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.
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*
Adding gluster-users as well.
-MS
-MS
Cheers,Gluster-devel@xxxxxxxxxxx
Vijay
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