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IOPS Estimation for EMC VNX5800

Written on:June 12, 2015
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In this article, we estimate the performance of the storage system controllers of the new EMC VNX5800 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 – 2 GHz.
  • The number of cores on one controller – 6.
  • The sum frequency calculation – 6×2 GHz = 12 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 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 «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 VNX5800 is 750.

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 VNX5800 and VNX7600 systems have the same number of SAS chips, so in theory, VNX5800 system can be used the same number of Flash drives, as in VNX7600.

However, we know that the processors, which are used in VNX5800, are weaker. Therefore, we need to use the ratio between total frequencies of controllers VNX5800 and VNX7600, so that we could correctly estimate the number of Flash disks in VNX5800.

We know an estimation of Flash drives quantity for VNX7600, it is equal to 120 Flash drives (see Article «IOPS Estimation for EMC VNX7600»).

The ratio between the total frequency of controllers is 12 / 17.6 ~ 0.68.

The estimation of Flash drives number for VNX5800 is equal to 120 * 0.68 ~ 82 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 30) 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 – 15.
  • 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:

04242015_VNX5800_IOPS_R99

The graphic representation results of calculation:

04242015_VNX5800_IOPS_R99_graph

Total:

Max IOPS is 365777.
Max IOPS for one controller is about 182889.
The ratio IOPS/GHz is about 15241.
The ratio IOPS/GB is 0,794.

Real Flash storage capacity is about 45 TB.
Real SAS 10K storage capacity is 405 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 with the new result is about 34%.

An estimation with FastCache:

04242015_VNX5800_IOPS_R99_FC

The graphic representation results of calculation:

04242015_VNX5800_IOPS_R99_FC_graph

Total:

Max IOPS is 367795.
Max IOPS for one controller is about 183898.
The ratio IOPS/GHz is 15325.
The ratio IOPS/GB is 0,919.

Real FastCache capacity is 2680 GB
Real Flash storage capacity is about 28 TB.
Real SAS 10K storage capacity is 360 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).

04242015_VNX5800_IOPS_R70

The graphic representation results of calculation:

04242015_VNX5800_IOPS_R70_graph

Total:

Max IOPS (DB like) is 198289.
Max IOPS for one controller (DB like) is about 99145.
The ratio IOPS per GHz is about 8262.
The ratio IOPS per GB is 0,431.

An estimation with FastCache:

04242015_VNX5800_IOPS_R70_FC

The graphic representation results of calculation:

04242015_VNX5800_IOPS_R70_FC_graph

Total:

Max IOPS (DB like) is 223796.
Max IOPS for one controller (DB like) is 111898.
The ratio IOPS per GHz is 9323.
The ratio IOPS per GB is 0,559.

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