Commit f875da40 authored by Simon A. F. Lund's avatar Simon A. F. Lund Committed by Jim Harris
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examples/nvme_fio_plugin: update ZNS section of README 



Signed-off-by: default avatarSimon A. F. Lund <simon.lund@samsung.com>
Change-Id: I99c82490811314201b53dde59e586538835e0840
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4950


Reviewed-by: default avatarJim Harris <james.r.harris@intel.com>
Reviewed-by: default avatarNiklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Community-CI: Mellanox Build Bot
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
parent aae84b1f

examples/nvme/fio_plugin/README.md

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@@ -116,3 +116,33 @@ To your fio-script, also have a look at script-examples provided with fio: 


    fio/examples/zbd-seq-read.fio

    fio/examples/zbd-rand-write.fio



## Maximum Open Zones



Zoned Namespaces has a resource constraint on the amount of zones which can be in an opened state at

any point in time. You can control how many zones fio will keep in an open state by using the

``--max_open_zones`` option.



The SPDK/NVMe fio io-engine will set a default value if you do not provide one.



## Maximum Active Zones



Zoned Namespaces has a resource constraint on the number of zones that can be active at any point in

time. Unlike ``max_open_zones``, then fio currently do not manage this constraint, and there is thus

no option to limit it either.



When running with the SPDK/NVMe fio io-engine you can be exposed to error messages, in the form of

completion errors, with the NVMe status code of 0xbd ("Too Many Active Zones"). To work around this,

then you can reset all zones before fio start running its jobs by using the engine option:



    --initial_zone_reset=1



## Shared Memory Increase



If your device has a lot of zones, fio can give you errors such as:



    smalloc: OOM. Consider using --alloc-size to increase the shared memory available.



This is because fio needs to allocate memory for the zone-report, that is, retrieve the state of

zones on the device including auxiliary accounting information. To solve this, then you can follow

fio's advice and increase ``--alloc-size``.