In this article, we estimate the performance of the storage system controllers of IBM Storwize V7000 Gen1 for different workload profiles, as well as other parameters of IOPS per GHz, IOPS per GB.
In the article «IBM Storwize V7000 Gen2» it was noted that it was not necessary to consider 4 controller pairs, which were interrelated with common management, as a single storage system. Therefore, all our calculations are only applicable to one controller pair or IO-group in the terminology of IBM.
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 – 2,13 GHz.
- The number of cores on one controller – 4.
- The sum frequency calculation – 4×2,13 GHz = 8,52 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 15.2 GHz x 10,000 IOPS / GHz, we obtain a rough estimation 85200 IOPS per controller. Thus, the performance of a pair of controllers is equal to 170400 IOPS. We can use these rough estimates for self-examination.
- We take information about recommended configurations of RAID groups in «V7000 Implementation Guide»:
- RAID 5 SSD are used in the configuration 7+1.
- RAID 5 SAS are used in the configuration 7+1.
- Max disk drive quantity for one pair of controllers is 240.
In the article “IOPS Estimation for IBM V7000 Gen2» the configuration with 48 Flash drives (2 disk shelves) is used for performance calculation. The performance of V7000 Gen1 is 2 time less than V7000 Gen2, therefore we will use 24 Flash drives for our calculation.
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 – RAID5 7+1.
- The quantity of RAID groups for Flash drives – 3.
- The configuration for RAID groups of SAS 15K drives – RAID5 7+1.
- The quantity of RAID groups for SAS 15K drives – 26.
Max IOPS for one IO-group is 117903.
Max IOPS for one controller is 58952.
The ratio of IOPS per GHz is 6919.
The ratio of IOPS per GB is 1,047.
Real Flash storage capacity is about 15 TB.
Real SAS 15K storage capacity is about 95 TB.
Let’s compare this result with a rough estimation, which we did in the beginning of this article. Then we got 85200 IOPS for one controller. The difference from the new result is 31%.
The big difference occurs due to CPU performance reserve which is needed for virtualization of external storages.
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).
Max IOPS for one IO-group (DB like) is 63916.
Max IOPS for one controller (DB like) is 31958.
The ratio of IOPS per GHz is 3751.
The ratio of IOPS per GB is 0,568.
The real capacity of disk space on Flash and SAS drives is the same.