Fundamentally, the metrics that describe the IO the OSD performs in
response to a recovery operation should be the same as the metrics for
client I/O. So in the context of a recovery operation, one OSD would
report a read (recovery source) and another report a write (recovery
target), together with their corresponding num_bytes. To my mind this
provides transparency, and maybe helps potential automation.
On Mon, Mar 13, 2017 at 1:13 AM, John Spray <jspray@xxxxxxxxxx> wrote:
> On Sat, Mar 11, 2017 at 9:24 PM, Paul Cuzner <pcuzner@xxxxxxxxxx> wrote:
>> On Sun, Mar 12, 2017 at 9:49 AM, John Spray <jspray@xxxxxxxxxx> wrote:
>>> On Fri, Mar 10, 2017 at 8:52 PM, Paul Cuzner <pcuzner@xxxxxxxxxx> wrote:
>>>> Thanks John
>>>>
>>>> This is weird then. When I look at the data with client load I see the
>>>> following;
>>>> {
>>>> "pool_name": "default.rgw.buckets.index",
>>>> "pool_id": 94,
>>>> "recovery": {},
>>>> "recovery_rate": {},
>>>> "client_io_rate": {
>>>> "read_bytes_sec": 19242365,
>>>> "write_bytes_sec": 0,
>>>> "read_op_per_sec": 12514,
>>>> "write_op_per_sec": 0
>>>> }
>>>>
>>>> No object related counters - they're all block based. The plugin I
>>>> have rolls-up the block metrics across all pools to provide total
>>>> client load.
>>>
>>> Where are you getting the idea that these counters have to do with
>>> block storage? What Ceph is telling you about here is the number of
>>> operations (or bytes in those operations) being handled by OSDs.
>>>
>>
>> Perhaps it's my poor choice of words - apologies.
>>
>> read_op_per_sec is read IOP count to the OSDs from client activity
>> against the pool
>>
>> My point is that client-io is expressed in these terms, but recovery
>> activity is not. I was hoping that both recovery and client I/O would
>> be reported in the same way so you gain a view of the activity of the
>> system as a whole. I can sum bytes_sec from client i/o with
>> recovery_rate bytes_sec, which is something, but I can't see inside
>> recovery activity to see how much is read or write, or how much IOP
>> load is coming from recovery.
>
> What would it mean to you for a recovery operation (one OSD sending
> some data to another OSD) to be read vs. write?
>
> John
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