We can use iotunev2 (or any other I/O generator) to test for the limits
of the disks for the i2 and i3 instance classes. The values I got here
are the values I got from ~5 invocations of the (yet to be upstreamed)
iotune v2, with the IOPS numbers rounded for convenience of reading.
During the execution, I verified that the disks were saturated so we
can trust these numbers even if iotunev2 is merged in a different form.
The numbers are very consistent, unlike what we usually saw with the
first version of iotune.
Previously, we were just multiplying the concurrency number by the
number of disks. Now that we have better infrastructure, we will
manually test i3.large and i3.xlarge, since their disks are smaller
and slower.
For the other i3, and all instances in the i2 family storage scales up
by adding more disks. So we can keep multiplying the characteristics of
one known disk by the number of disks and assuming perfect scaling.
Example for i3, obtained with i3.2xlarge:
read_iops = 411k
read_bandwidth = 1.9GB/s
So for i3.16xlarge, we would have read_iops = 3.28M and 15GB/s - very
close to the numbers advertised by AWS.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
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