In this article, we estimate controller’s performance of low end storage system NetApp FAS8020 for different workload profiles, as well as other parameters of IOPS per GHz, IOPS per GB.

All the performed calculations are based on the methodology described in the article «Methodology of IOPS Estimation».

Let’s gather all necessary information needed for a calculation.

- The frequency of processor cores – 2 GHz.
- The number of cores on one controller – 6.
- The number of processors on one controller – 1.
- The sum frequency calculation – 2x6x1 GHz = 12 GHz.
- At this stage we can get a rough estimation of IOPS for one controller. To do this, it is necessary to use the relation between the number of IOPS and sum frequency of the controller. This value is specified in the methodology (10000 IOPS / GHz). Multiply 12 GHz x 10000 IOPS / GHz, we obtain a rough estimation 120000 IOPS per controller. Thus, the performance of a pair of controllers is equal to 240000 IOPS. We can use these rough estimates for self-examination.
- We take information about recommended configurations of RAID groups in «Implementation Guide»:
- RAID-DP SSD are used in the configuration 14+2.
- RAID-DP SAS are used in the configuration 14+2.

- Max disk drive quantity for one pair of controllers is 480.

In the article «NetApp FAS8xxx : a Brief Overview» it’s noted that 65 Flash disks of 400GB can be installed in the system FAS8020. However the max Flash disks for All-Flash configuration, defined on the level of software, is 240.

For the calculation we will use 62 Flash disks in the configuration RAID-DP 14+2 and 12+2 in accordance with the recommendation of NetApp.

**The estimation for max IOPS (Cache Read Miss)**

Let’s set the values for the estimation:

• Read operations – 99%.

• The configuration for RAID groups of Flash drives – RAID-DP 14+2.

• The quantity of RAID groups for Flash drives – 8.

• We will use one disk group RAID-DP 12+2 for rest Flash disks.

• The configuration for RAID groups of SAS 10K drives – RAID-DP 14+2.

• The quantity of RAID groups for SAS 10K drives – 25.

The graphic representation results of calculation:

Max IOPS for one HA-pair is **263810**.

Max IOPS for one controller is **131905**.

The ratio of IOPS/GHz is **10992**.

The ratio of IOPS/GB is **0,877**.

Real Flash storage capacity is about 19 TB.

Real SAS 15K storage capacity is about 275 TB.

Let’s compare this result with a rough estimation, which we did in the beginning of this article. Then we got 120000 IOPS for one controller. The difference from the new result is** 9**%.

That was a good estimation, taking into account that it had been made only on the basis of knowledge about the frequency of processor cores and their quantities on one controller.

**The IOPS estimation for DB like workload (Cache Read Miss)**

The Initial parameters are the same, but the percentage of read operations is different. A typical ratio between read and write operations is equal to 70/30 for databases (OLTP workload).

The graphic representation results of calculation:

Max IOPS for one HA-pair (DB like) is **110800**.

Max IOPS for one controller (DB like) is **55400**.

The ratio of IOPS per GHz is **4617**.

The ratio of IOPS per GB is **0,368**.

The real capacity of disk space on Flash and SAS drives is the same.

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