thank you very much, Craig, for your clear explanation against my questions.
Now I am very clear about the concept of pools in ceph.
But I have two small questions:
1. How does the deployer decide that a particular type of information will be
stored in a particular pool? Are there any settings at the time of creation of
pool that a deployer should make to ensure that which type of data will be
stored in which pool?
2. How does an end-user specify that his/her data will be stored in which pool?
how can an end-user come to know which pools are stored on SSDs or on HDDs,
what are the properties of a particular pool?
Thanks again, Please help to clear these confusions also.
Regards
Pragya Jain
On Sunday, 13 July 2014 5:04 AM, Craig Lewis <[email protected]> wrote:
>
>
>I'll answer out of order.
>
>
>#2: rdb is used for RDB images. data and metadata are used by CephFS.
>RadosGW's default pools will be created the first time radosgw starts up. If
>you aren't using RDB or CephFS, you can ignore those pools.
>
>
>#1: RadosGW will use several pools to segregate it's data. There are a couple
>pools for store user/subuser information, as well as pools for storing the
>actual data. I'm using federation, and I have a total of 18 pools that
>RadosGW is using in some form. Pools are a way to logically separate your
>data, and pools can also have different replication/storage settings. For
>example, I could say that the .rgw.buckets.index pool needs 4x replication and
>is only stored on SSDs, while .rgw.bucket is 3x replication on HDDs.
>
>
>#3: In addition to #1, you can setup different pools to actually store user
>data in RadosGW. For example, an end user may have some very important data
>that you want replicated 4 times, and some other data that needs to be stored
>on SSDs for low latency. Using CRUSH, you would create the some rados pools
>with those specs. Then you'd setup some placement targets in RadosGW that use
>those pools. A user that cares will specify a placement target when they
>create a bucket. That way they can decide what the storage requirements are.
>If they don't care, then they can just use the default.
>
>
>Does that help?
>
>
>
>
>
>On Thu, Jul 10, 2014 at 11:34 PM, pragya jain <[email protected]> wrote:
>
>hi all,
>>
>>
>>I have some very basic questions about pools in ceph.
>>
>>
>>According to ceph documentation, as we deploy a ceph cluster with radosgw
>>instance over it, ceph creates pool by default to store the data or the
>>deployer can also create pools according to the requirement.
>>
>>
>>Now, my question is:
>>1. what is the relevance of multiple pools in a cluster?
>>i.e. why should a deployer create multiple pools in a cluster? what should be
>>the benefits of creating multiple pools?
>>
>>
>>2. according to the docs, the default pools are data, metadata, and rbd.
>>what is the difference among these three types of pools?
>>
>>
>>3. when a system deployer has deployed a ceph cluster with radosgw interface
>>and start providing services to the end-user, such as, end-user can create
>>their account on the ceph cluster and can store/retrieve their data to/from
>>the cluster, then Is the end user has any concern about the pools created in
>>the cluster?
>>
>>
>>Please somebody help me to clear these confusions.
>>
>>
>>regards
>>Pragya Jain
>>_______________________________________________
>>ceph-users mailing list
>>[email protected]
>>http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>>
>
>
>
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