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IOPS Estimation for EMC VNX5200

Written on:November 19, 2014
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In this article, we estimate the performance of the storage system controllers of the new EMC VNX5200 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 the calculation.

  • The frequency of processor cores – 1,2 GHz.
  • The number of cores on one controller – 4.
  • The sum frequency calculation – 4×1,2 GHz = 4,8 GHz.
  • At this stage we can get a rough upper 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). Let’s multiply 7,2 GHz x 10000 IOPS / GHz, we obtain a rough estimation 48000 IOPS per controller. Thus, the performance of a pair of controllers is equal to 96000 IOPS. We can use these rough estimates for self-examination.
  • We take information about recommended configurations of RAID groups in «View on new EMC VNX2 series»:
    • RAID 5 SSD are used in the configuration 4+1 or 8+1.
    • RAID 5 SAS are used in the configuration 4+1 or 8+1.
  • Max disk drive quantity for VNX5200 is 125.

Now we need to estimate the maximum number of Flash drives, which will be aligned with the performance of controllers.

In the article «View on new EMC VNX2 series», we mentioned that VNX5200 and VNX5400 systems have the same number of SAS chips, so in theory, VNX5200 system can be used the same number of Flash drives, as in VNX5400. However, we know that the processors, which are used in VNX5200, are weaker. Therefore, we need to use the ratio between total frequencies of controllers VNX5200 and VNX5400, so that we could correctly estimate the number of Flash disks in VNX5200.

We know an estimation of Flash drives quantity for VNX5400, it is equal to 45 Flash drives (see Article «IOPS Estimation for EMC VNX5400»).

The ratio between the total frequency of controllers is 4.8 / 7.2 ~ 0.67.

The estimation of Flash drives number for VNX5400 is equal to 45 * 0.67 ~ 30 Flash drives.

The use of two types of Flash drives (SLC and MLC) in VNX2 is possible, so we will make two configurations:

  • SLC drives 200GB for FastCache (max 6) and MLC drives 800GB
  • MLC drives 800GB.

The estimation for max IOPS (Cache Read Miss)

Let’s set the basic values for the estimation:

  • Read operations – 99%.
  • The configuration for FastCache (SLC) – RAID10 1+1.
  • The quantity of groups – 3.
  • The configuration for MLC drives – RAID5 4+1 or 8+1.
  • The configuration for SAS 10K – RAID5 4+1 or 8+1.

As a result we have got such a calculation:

11172014_VNX5200_IOPS

Total:

Max IOPS is 115049.
Max IOPS for one controller is 57525.
The ratio IOPS/GHz is 11984.
The ratio IOPS/GB is 2,064.

Real Flash storage capacity is about 17 TB.
Real SAS 10K storage capacity is 38 TB.

Let’s compare this result with a rough estimation, which we did in the beginning of this article. Then we got 48000 IOPS for one controller. The difference with the new result is about 17%.

An estimation with FastCache:

11172014_VNX5200_IOPS_FC

Total:

Max IOPS is 115452.
Max IOPS for one controller is 57726.
The ratio IOPS/GHz is 12026.
The ratio IOPS/GB is 2,19.

Real FastCache capacity is 536 GB
Real Flash storage capacity is about 14 TB.
Real SAS 10K storage capacity is 38 TB.

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

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

11172014_VNX5200_IOPS_R70

Total:

Max IOPS (DB like) is 62368.
Max IOPS for one controller (DB like) is 31184.
The ratio IOPS per GHz is about 6497.
The ratio IOPS per GB is 1,119.

An estimation with FastCache:

11172014_VNX5200_IOPS_FC_R70

Total:

Max IOPS (DB like) is 67470.
Max IOPS for one controller (DB like) is 33705.
The ratio IOPS per GHz is 7022.
The ratio IOPS per GB is 1,28.

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