Re: deleting objects from a pool

[David Zafman <dzafman@redhat.com>]

This is a dangerous command because it can remove all your objects. At 
least it can only do one namespace at a time.  It was intended to 
cleanup rados bench runs, and is dangerous because it doesn't require 
extra hoops like rados rmpool does.

I'm tempted to disallow a usage this way with empty --prefix/--run-name 
arguments.

David

On 6/25/15 10:40 PM, Podoski, Igor wrote:
> Hi David,
>
> You're right, now I see adding --run-name "" will clean all benchmark data from specified namespace, so you can run command only once.
>
> rados -p <poolname> -N <namespace> cleanup --prefix "" --run-name ""
>
> Regards,
> Igor.
>
>
> -----Original Message-----
> From: David Zafman [mailto:dzafman@redhat.com]
> Sent: Friday, June 26, 2015 3:46 AM
> To: Podoski, Igor; Deneau, Tom; Dałek, Piotr; ceph-devel
> Subject: Re: deleting objects from a pool
>
>
> If you have rados bench data around, you'll need to run cleanup a second time because the first time the "benchmark_last_metadata" object will be consulted to find what objects to remove.
>
> Also, using cleanup this way will only remove objects from the default namespace unless a namespace is specified with the -N option.
>
> rados -p <poolname> -N <namespace> cleanup --prefix ""
>
> David
>
> On 6/24/15 11:06 PM, Podoski, Igor wrote:
>> Hi,
>>
>> It appears, that cleanup can be used as a purge:
>>
>> rados -p <poolname> cleanup  --prefix ""
>>
>> Regards,
>> Igor.
>>
>>
>> -----Original Message-----
>> From: ceph-devel-owner@vger.kernel.org
>> [mailto:ceph-devel-owner@vger.kernel.org] On Behalf Of Deneau, Tom
>> Sent: Wednesday, June 24, 2015 10:22 PM
>> To: Dałek, Piotr; ceph-devel
>> Subject: RE: deleting objects from a pool
>>
>> I've noticed that deleting objects from a basic k=2 m=1 erasure pool is much much slower than deleting a similar number of objects from a replicated size 3 pool (so the same number of files to be deleted).   It looked like the ec pool object deletion was almost 20x slower.  Is there a lot more work to be done to delete an ec pool object?
>>
>> -- Tom
>>
>>
>>
>>> -----Original Message-----
>>> From: ceph-devel-owner@vger.kernel.org [mailto:ceph-devel-
>>> owner@vger.kernel.org] On Behalf Of Dalek, Piotr
>>> Sent: Wednesday, June 24, 2015 11:56 AM
>>> To: ceph-devel
>>> Subject: Re: deleting objects from a pool
>>>
>>>> -----Original Message-----
>>>> From: ceph-devel-owner@vger.kernel.org [mailto:ceph-devel-
>>>> owner@vger.kernel.org] On Behalf Of Deneau, Tom
>>>> Sent: Wednesday, June 24, 2015 6:44 PM
>>>>
>>>> I have benchmarking situations where I want to leave a pool around
>>>> but delete a lot of objects from the pool.  Is there any really fast
>>>> way to do
>>> that?
>>>> I noticed rados rmpool is fast but I don't want to remove the pool.
>>>>
>>>> I have been spawning multiple threads, each deleting a subset of the
>>> objects
>>>> (which I believe is what rados bench write does) but even that can
>>>> be very slow.
>>> For now, apart from "rados -p <poolname> cleanup" (which doesn't
>>> purge the pool, but merely removes objects written during last
>>> benchmark run), the only option is by brute force:
>>>
>>> for i in $(rados -p <poolname> ls); do (rados -p <poolname> rm $i
>>> &>/dev/null &); done;
>>>
>>> There's no "purge pool" command in rados -- not yet, at least. I was
>>> thinking about one, but never really had time to implement one.
>>>
>>> With best regards / Pozdrawiam
>>> Piotr Dałek
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