NEC PerforCache. Influence on M-Series Disk Array Behavior and Performance. Version 1.0

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1 NEC PerforCache Influence on M-Series Disk Array Behavior and Performance. Version 1.0

2 Preface This document describes L2 (Level 2) Cache Technology which is a feature of NEC M-Series Disk Array implemented as NEC PerforCache. This document describes the types, purpose, configuration and benefits of L2 cache. This document also explains the performance test which was conducted, the various parameters, and analyses the test results in detail, which helps people understand the behavior of L2 cache and determine the best conditions with which L2 cache can be used to boost storage performance. Influence on NEC M-Series Disk Array Behavior & Performance 1

3 Contents: 1. Introduction What is SSD How SSD serves the Storage System What is NEC PerforCache (L2 Cache) Purpose of PerforCache Types of PerforCache PerforCache configuration Benefits of PerforCache Improving Reducing Operational Cost Multiple applications can be served simultaneously Overall load on traditional disk drives is reduced PerforCache Operation (How it Works) PerforCache Test Performance and Analysis Test Scenarios Test Parameters Test Results Test Analysis Best Performance Condition Summary and Conclusion Appendix A Appendix B Influence on NEC M-Series Disk Array Behavior & Performance 2

4 1. Introduction System performance depends on many elements, one of the most important of which is the access time of its hard disk drive (HDD). Response times may slow down if random access load is concentrated on a single disk array. NEC s PerforCache is a feature provided to solve this problem. NEC does this by using SSD (Solid State Drive) technology in a unique way What is SSD Abbreviated as SSD, a solid state drive is a high-performance plug-and-play storage device that contains no moving parts. SSD components include DRAM or EEPROM memory boards, a memory bus board, a CPU and a battery card. Since they contain their own CPUs to manage data storage, and they also have no heads or platters and incur only very small seek latencies, they are much faster (18MBps for SCSI-II and 35 MBps for UltraWide SCSI interfaces) than conventional rotating hard disks. This is how SSD drives produce such high I/O rates. Solid-state drives (SSDs), also known as Enterprise Flash Drives, have much better performance than HDDs however SSDs are more costly per gigabyte How SSD serves the Storage System In the storage system context a question arises: how does one best deploy SSD drive technology such that they provide opportunities for tremendous performance improvements? This issue is addressed by using tiered storage technology. Tiered storage is an arrangement where all logical disks will move automatically to the most optimum storage device in the array system. Tiered storage is dependent upon data access frequency patterns. NEC s Data Allocation Optimization function is a feature which provides this functionality. Another way to deploy SSD technology in a beneficial way is to use SSD drives as a cache. With respect to PerforCache, caching is a technique which allows the controller inside the storage system to use SSD technology as a cache in front of traditional disk storage. The controller identifies any frequently accessed data, sometimes called "hot data," and automatically moves it to the solid-state media. The basic idea is to improve performance by getting the hot data onto the fastest media. This has the effect of increasing I/O performance and decreasing I/O latency. As I/O patterns change over time, the controllers automatically observe the data that is most frequently accessed and moves it onto the fastest media, without any intervention on the part of the user or the administrator. Influence on NEC M-Series Disk Array Behavior & Performance 3

5 NEC has found a way to use SSD technology as a cache with the aim of improving traditional hard disk drive-based storage system performance. Caching differs from tiered storage in that it doesn t use solid-state memory as a permanent location for data storage, rather this technology redirects read and write requests from disk to cache on-demand, serving to accelerate performance. This is especially true for random I/O, a notoriously work-intensive operation for traditional drive architectures. NEC s PerforCache technology benefits any application whose data is considered hot, the performance improvement is even greater as more data is placed into the cache. 2. What is NEC PerforCache (L2 Cache) PerforCache or L2 cache (Level 2 Cache) is a feature of NECs Storage products. PerforCache determines frequently accessed data or hotspot contained in storage and then places a copy of the data into the L2 cache. This allows subsequent accesses to this hot data to realize the high I/O access speed and other benefits of L2 cache while not removing the data from its original location on the storage device. SSD devices are inserted into the Storage array chassis just as any other drive. Simply inserting the SSD devices into the proper drive bay makes them available for use by PerforCache Purpose of PerforCache NEC s PerforCache uses SSD devices in three specific ways: it is used as read cache, write cache, or persistent write cache. These are described below: Read cache: Data that is frequently read is stored in by PerforCache. If data already exists in the L1 cache (*1) when the next read request for this data is made, the data is then copied to PerforCache. Data held in PerforCache can be accessed much more quickly than it can be accessed from traditional HDD (Hard Disk Drive) architectures. PerforCache is very effective for operations involving frequent read based transactions such as those associated with database indexes or a supporting network based virtual boot drives in a desktop environment. Write cache: Frequent write operations are also facilitated by using PerforCache. When write transactions are initiated PerforCache writes the incoming data to its associated SSD drives before moving the data to the main array. This allows incoming write transactions to be handled much more quickly. Influence on NEC M-Series Disk Array Behavior & Performance 4

6 Persistent write: PerforCache ensures data integrity even during a possible hardware fault. Typically, if one of the controllers experiences a failure, its L1 cache usually enters a writethrough (*2) state in order to maintain the data integrity. This result in an overall performance decrease for incoming write transactions because the controller can no longer cache the incoming transactions in memory. PerforCache allows the failed controller to use its SSD device as a type of temporary L1 cache. The afflicted controller may remain in writethrough mode and not adversely affect performance because the PerforCache is accepting all of the incoming write transactions while allowing the controller to continue to write data to the array at the same time. (*1) The L1 cache means a cache that is bound to the cache module. (*2) Write-through is a mode of I/O in which data is written to the physical disk in addition to simultaneously being written to cache Types of PerforCache PerforCache offers performance oriented options for initial configuration. There are two options: 1. Read/Write: A general purpose cache used for reads, writes, or persistent writes. 2. Read only: A read specific cache that is used primarily as read cache. Persistent writes are also supported. Select either of these two types of cache at the time of L2 cache binding. Following table shows the characteristics of different type of PerforCache: Type Read/Write 2 or 4 No. of SSD Required Redundancy Available space Duplication Half of the Total SSD Capacity Read only 1 or 2 None Total SSD Capacity Table 2.1. Characteristic Depending on the PerforCache Configuration Fault Tolerance If one SSD goes down PerforCache cannot be used continuously as a write cache, but it can be used continuously used as a read cache or for persistent writes. If two or more SSDs go down, PerforCache cannot be used at all. If one or more SSDs go down PerforCache cannot be used at all. Influence on NEC M-Series Disk Array Behavior & Performance 5

7 2.3. PerforCache configuration PerforCache consists of SSD devices configured as an L2 cache drive pool. Logical disks from this pool are then allocated for use by PerforCache. Installing the PerforCache license, adding the SSD drives and then completing the configuration steps are the basic steps in PerforCache installation. Keep in mind that a L2 cache pool cannot use any of the physical disks numbered 0 to 3 which are installed as part of the main disk array. In the case of manual disk selection, if there are disks of differing sizes, the PerforCache will be created using the smallest disk as a base. Also, only one PerforCache can be created per disk array. The following figure shows a configuration example of a L2 cache binding. Figure 2.1. Configuration Example of a L2 cache binding 3. Benefits of PerforCache 3.1. Improving SSDs have superior IO performance. This makes them very suitable for caching operations. PerforCache provides better performance by utilizing the performance benefits of SSD s. SSD devices also offer the benefit of not incurring performance degradation based on the type of data access (sequential VS random) because they perform equally well in all access contexts. Any enterprise which experiences performance issues using current non-cached, non-ssd array architectures will benefit by deploying PerforCache. Influence on NEC M-Series Disk Array Behavior & Performance 6

8 3.2. Reducing Operational Cost With traditional disk drive architectures it was necessary to distribute heavy loads among multiple arrays in order to handle the traffic volume adequately. However, using a large number of arrays and disks for load distribution results in high power consumption during operation. This served to address the performance concerns but also served to raise the operational cost. With PerforCache technology, response time can be improved by adding a few SSD drives instead of installing many traditional drives or new arrays. There is the added benefit of, on a drive for drive basis, SSD drives consuming less power Multiple applications can be served simultaneously Multiple applications can benefit from PerforCache simultaneously as it automatically detects data hotspots anywhere in the array, there is no application specific tuning required Overall load on traditional disk drives is reduced Since frequently accessed data is accessed from the SSD drives controlled by PerforCache, the overall load and constant demand on the traditional disks is reduced adding to power savings and further reducing operational costs. 4. PerforCache Operation (How it Works) Each controller in the array has access to PerforCache and realizes the benefits of SSDs. Data which is cached to the L1 cache (level 1 cache that is bound with the controller) are also mirrored to PerforCache when operational conditions are met. Each controller has a map table which resides on its L1 cache. This table references data within the PerforCache. A copy of this map table is also maintained in PerforCache itself for safety. The L2 cache map table is simply an address table which contains a reference, in 32 KB chunks, describing PerforCache data location information. When the PerforCache bind is executed, the L2 cache pool and three logical disks for PerforCache are configured. One Logical disk is for controller 0, the second is for controller 1, and last one is designated as a persistent write area. Influence on NEC M-Series Disk Array Behavior & Performance 7

9 Figure 4.1. L2 cache binding Read Operation Whenever a read transaction is requested from the host application, it will first hit on the L1 cache. If the data is available in L1 cache the transaction will be serviced using this data. In case the data is not available in L1 cached then the controller will check the L2 cache map table to see if the requested data has already been promoted to L2 cache. If the data was not promoted, the read request will read the data directly from the storage device. Data which is read from the storage device is always populated to L1 cache during the first read. A LRU (Least Recently Used) algorithm is applied to ensure space is available on the L1 cache, removing stale data (no recent hits). If the read request is more than the pre-determined threshold then the hit data in L1 cache is moved to L2 cache and the L2 cache map table will be updated. L1 cache can be freed at this point as the data is available from L2 cache. The same LRU algorithm used for L1 cache maintenance is applied to L2 cache in order to ensure that L2 cache space is available. If the cache data in L2 cache is stale it is removed from L2 cache. Influence on NEC M-Series Disk Array Behavior & Performance 8

10 Figure 4.2. Read Operation Write Operation When servicing write transaction requests, the data is transferred from the initiating host and stored in L1 cache as dirty data and is written to the storage array periodically. If L1 cache is full and the dirty page count will exceed the L1 threshold limit, the data from the L1 cache is moved to L2 cache as dirty pages. This process serves to increase overall performance because incoming data is written to the SSD in L2 cache prior to being written to the storage device. Dirty pages that were stored on L2 cache will be flushed to L1 cache periodically, whenever there is enough space on L1 cache, at this point the data is finally written to the storage device. Figure 4.3. Write Operation Influence on NEC M-Series Disk Array Behavior & Performance 9

11 Persistent Write Function Each controller in the storage system has its own cache (DRAM), also known as L1 cache. If one controller of the storage system goes down, write performance from host to storage will also generally go down since the controller will go into the write-through state in order to maintain data integrity. This is a condition in which data is written to the physical disk as well as L1 cache. NEC s PerforCache allows a faulted controller to substitute PerforCache SSD drives for L1 cache. This serves to avoid client disconnect or performance degradation during controller faults. Figure 4.4. Persistent Write Function 5. PerforCache Test Performance and Analysis Tests were executed with the aim of measuring the performance of PerforCache in various test scenarios. The details about specific parameters and scenarios as well as suggestions on the optimal contexts are described here Test Scenarios Tests were performed detailing the following three scenarios: 1. With Read Only PerforCache mode: In this scenario test was performed while PerforCache was enabled in Read Only mode. 2. With Read Write PerforCache mode: In this scenario tests were performed while PerforCache was enabled in Read Write mode. 3. With PerforCache Off or PerforCache disabled: In this scenario PerforCache was disabled. Tests were performed using L1 cache only. Influence on NEC M-Series Disk Array Behavior & Performance 10

12 5.2. Test Parameters A very common and basic storage benchmark is Input/output operations per second (IOPS). Generating IOPs against a storage device can be useful for measuring the performance and response time of a storage system. These metrics are generally measured from transaction start until transaction completion, response time is generally measured in milliseconds. A variety of operational parameters are measured and reported here. In many cases, performance is tested across a variety of workload patterns and relative intensity levels are used to gauge the system's response for a range of conditions. For example, storage system performance can be evaluated with read-intensive, write-intensive or mixed workloads. The data here represents as many viable workload contexts as seemed justified. Following table shows the parameters which were used for storage performance measurement testing: Parameter Type Parameters used No. of Logical Disk(LD) / Controller 1 LD/1 Controller and 2 LD/2 Controller RAID Type RAID 5 and RAID 6 Access Area 8GB, 16GB,32GB and Global Access Block Size 4KB, 8KB, 32KB and 64KB Read Write Ratio 100%R, 80%R20%W, 60%R40%W and 100%W Random/Sequential Distribution Random Access Table 5.1. Operating Parameters Tables below shows the type, size, and number of Logical Disks (LD) and Physical Disks (PD) used. For Logical Volumes (RAID 5) RAID5/50 (n+p) minimum setup: n=2, actual setup: n=10 Scenario Type RW Cache-1 Cont. RW Cache-2 Cont. RO Cache-1 Cont. RO Cache-2 Cont. HDD Type Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 SAS rpm rev 202 SAS rpm rev 202 SAS rpm rev 202 SAS rpm rev 202 HDD Size 2.5 inch 450 GB, assigned to 2.5 inch 450 GB, assigned to 2.5 inch 450 GB, assigned to 2.5 inch 450 GB, assigned to Storage System: GB Storage System: GB Storage System: GB Storage System: GB No. of PD No. of LD LD Size 207 GB 207 GB 207 GB 207 GB Table 5.2. Physical Disks & Logical Disks Details (RAID5). Influence on NEC M-Series Disk Array Behavior & Performance 11

13 Scenario Type RW Cache-1 Cont. RW Cache-2 Cont. RO Cache-1 Cont. RO Cache-2 Cont. Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 Hitachi HUC106045CSS600 HDD Type SAS rpm rev 202 SAS rpm rev 202 SAS rpm rev 202 SAS rpm rev 202 HDD Size For Logical Volumes (RAID 6) RAID6/60 (n+pq) minimum setup: n=4, actual setup: n=4 2.5 inch 450 GB, assigned to Storage System: GB 2.5 inch 450 GB, assigned to Storage System: GB 2.5 inch 450 GB, assigned to Storage System: GB No. of PD No. of LD LD Size 207 GB 207 GB 207 GB 207 GB Table 5.3. Physical Disks & Logical Disks Details (RAID6). 2.5 inch 450 GB, assigned to Storage System: GB For L2 Cache RAID1/10 (n+mirror) n=1, actual setup: n=1 Scenario Type RW Cache-1 Cont. RW Cache-2 Cont. RO Cache-1 Cont. RO Cache-2 Cont. HDD Type SSD STEC ZEUS IOPs EVT NEC SSD STEC ZEUS IOPs EVT NEC SSD STEC ZEUS IOPs EVT NEC SSD STEC ZEUS IOPs EVT NEC rev N10E rev N10E rev N10E rev N10E HDD Size 2.5 inch 100 GB, assigned to 2.5 inch 100 GB, assigned to 2.5 inch 100 GB, assigned to 2.5 inch 100 GB, assigned to Storage System87.6 GB Storage System87.6 GB Storage System87.6 GB Storage System87.6 GB No. of PD No. of LD LD Size 2x36 GB; 8 GB 2x36 GB; 8 GB 2x36 GB; 8 GB 2x36 GB; 8 GB Table 5.4. Physical Disks & Logical Disks Details (L2 cache) Test Results For detailed test results, refer to Appendix B on Page Test Analysis The resultant data sets here demonstrate areas where PerforCache brings the greatest overall improvement. Following are some relevant points demonstrated by the test results: Performance was increased nearly 800 % (depending upon conditions) with Read Write PerforCache enabled specifically on 60/40 and 80/20 Read/Write ratios. Performance was increased by decreasing overall access area. For Read Only Cache mode, 60/40 and 80/20 Read/Write ratios will give improved performance. For detailed analysis data and graphs, refer to Appendix A on page 24. Influence on NEC M-Series Disk Array Behavior & Performance 12

14 5.5. Best Performance Condition PerforCache will demonstrate the strongest performance gains under the following conditions: On 60/40 Read/Write ratio using 4K and 8 K Block size (A Real World Situation). Below data and graphs show the percentage improvement in performance using 60/40 Read/Write ratios on 4K and 8K Block size: 60% Read/40% Write, Random Access, Single Controller/1 LD, RAID 5 Figure 5.1. Figure 5.2. Influence on NEC M-Series Disk Array Behavior & Performance 13

15 60% Read/40% Write, Random Access, Dual Controller/2 LD, RAID 5 Figure 5.3. Figure % Read/40% Write, Random Access, Single Controller/1 LD, RAID 6 Figure 5.5. Influence on NEC M-Series Disk Array Behavior & Performance 14

16 Figure % Read/40% Write, Random Access, Dual Controller/2 LD, RAID 6 Figure 5.7. Figure 5.8. Influence on NEC M-Series Disk Array Behavior & Performance 15

17 On 80/20 Read Write ratio on 4K and 8 K block size. Data and graphs below show the percentage improvement in performance using 80/20 Read/Write ratios for 4K and 8K block size: 80% Read/20% Write, Random Access, Single Controller/1 LD, RAID 5 Figure 5.9. Figure Influence on NEC M-Series Disk Array Behavior & Performance 16

18 80% Read/20% Write, Random Access, Dual Controller/2 LD, RAID 5 Figure Figure % Read/20% Write, Random Access, Single Controller/1 LD, RAID 6 Figure Influence on NEC M-Series Disk Array Behavior & Performance 17

19 Figure % Read/20% Write, Random Access, Dual Controller/2 LD, RAID 6 Figure Figure Influence on NEC M-Series Disk Array Behavior & Performance 18

20 6. Summary and Conclusion NECs PerforCache is a feature of NEC M-Series Disk Array. By creating an L2 cache with enterprise flash drives (SSDs), NEC s M-Series Disk Array experiences decreased latency and increased I/O performance. These SSDs provide I/O improvement for the most frequently accessed data, providing SSD response speeds every time the data is accessed. PerforCache implementation will improve application performance by up to 800%*. Many different applications demand a greater level of performance than non-ssd storage devices can provide. PerforCache implementation is one of the most cost effective and performance oriented solutions for boosting application performance while also effectively reducing overall storage costs. (*depending on conditions & parameters) Influence on NEC M-Series Disk Array Behavior & Performance 19

21 Appendix A Following tables and graphs show the percentage change in the performance while enable Read Write PerforCache Conditions: 100% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 20

22 Conditions: 100% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 21

23 Conditions: 100% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 22

24 Conditions: 100% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 23

25 Influence on NEC M-Series Disk Array Behavior & Performance 24

26 Conditions: 80% Read/20% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 25

27 Conditions: 80% Read/20% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 26

28 Conditions: 80% Read/20% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 27

29 Conditions: 80% Read/20% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 28

30 Conditions: 60% Read/40% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 29

31 Conditions: 60% Read/40% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 30

32 Conditions: 60% Read/40% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 31

33 Influence on NEC M-Series Disk Array Behavior & Performance 32

34 Conditions: 60% Read/40% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 33

35 Conditions: 100% Read, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 34

36 Conditions: 100% Read, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 35

37 Conditions: 100% Read, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 36

38 Conditions: 100% Read, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 37

39 Influence on NEC M-Series Disk Array Behavior & Performance 38

40 Following tables and graphs show the performance comparison (IOPS & RT) between Read Write PerforCache and PerforCache disable (L2 cache off). Conditions: 100% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 39

41 Conditions: 100% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 40

42 Conditions: 100% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 41

43 Conditions: 100% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 42

44 Conditions: 80% Read 20% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 43

45 Conditions: 80% Read 20% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 44

46 Conditions: 80% Read 20% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 45

47 Conditions: 80% Read 20% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 46

48 Influence on NEC M-Series Disk Array Behavior & Performance 47

49 Conditions: 60% Read 40% Write, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 48

50 Conditions: 60% Read 40% Write, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 49

51 Conditions: 60% Read 40% Write, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 50

52 Conditions: 60% Read 40% Write, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 51

53 Influence on NEC M-Series Disk Array Behavior & Performance 52

54 Conditions: 100% Read, Random Access, Single Controller/1 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 53

55 Conditions: 100% Read, Random Access, Dual Controller/2 LD, RAID 5 Influence on NEC M-Series Disk Array Behavior & Performance 54

56 Conditions: 100% Read, Random Access, Single Controller/1 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 55

57 Conditions: 100% Read, Random Access, Dual Controller/2 LD, RAID 6 Influence on NEC M-Series Disk Array Behavior & Performance 56

58 Influence on NEC M-Series Disk Array Behavior & Performance 57

59 Appendix B Test Results with "Read Write" Cache Type (using 2 SSD 100 GB each) with 1 Controller & 1 LD PD No's, Type & Size: 10, Hitachi HUC106045CSS600 SAS rpm rev 202 & 2.5 inch 450 GB LD No's & Size: 1 LD of 207 GB (RAID 5) RAID5/50 (n+p) minimum setup: n=2, actual setup: n=10 Access Area 8 GB 16 GB 32 GB Global Access Block Size 1 KB 6 1 KB 6 1 KB 6 1 KB 6 Read Write Ratio Random/ Sequential Distribution IOPS Total IOPS Read IOPS Write IOPS Results with L1 + L2 Cache enabled I/O (ms) Avg. Total Avg. Read Avg. Write L1+L2 Hit Ratio L1 Hit Ratio L2 Paging Size 100% Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random Influence on NEC M-Series Disk Array Behavior & Performance 58

60 Test Results with "Read Write" Cache Type (using 2 SSD 100 GB each) with 1 Controller & 1 LD PD No's, Type & Size: 6, Hitachi HUC106045CSS600 SAS rpm rev 202 & 2.5 inch 450 GB LD No's & Size: 1 & 207 GB (RAID 6) RAID6/60 (n+pq) minimum setup: n=4, actual setup: n=4 Access Area 8 GB 16 GB 32 GB Global Access Block Size 32 KB 6 32 KB 6 32 KB 6 32 KB 6 Read Write Ratio Random/ Sequential Distribution IOPS Total IOPS Read IOPS Write IOPS Results with L1 + L2 Cache enabled I/O (ms) Avg. Total Avg. Read Avg. Write L1 Hit Ratio AVG L2 Paging Size AVG L2 Cache Max Dirty Page Ratio 100% Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random Influence on NEC M-Series Disk Array Behavior & Performance 59

61 Test Results with "Read Write" Cache Type (using 2 SSD 100 GB each) with 2 Controller & 2 LD PD No's, Type & Size: 10, Hitachi HUC106045CSS600 SAS rpm rev 202 & 2.5 inch 450 GB LD No's & Size: 2 & 207 GB (RAID 5) RAID5/50 (n+p) minimum setup: n=2, actual setup: n=10 Access Area 8 GB 16 GB 32 GB Global Access (200 GB) Block Size 1 KB 6 1 KB 6 1 KB 6 1 KB 6 Read Write Ratio Random/ Sequential Distribution IOPS Total IOPS Read IOPS Write IOPS Results with L1 + L2 Cache enabled I/O (ms) Avg. Total Avg. Read Avg. Write L1 Hit Ratio AVG L2 Paging Size AVG L2 Cache Max Dirty Page Ratio 100% Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random Influence on NEC M-Series Disk Array Behavior & Performance 60

62 Test Results with "Read Write" Cache Type (using 2 SSD 100 GB each) with 2 Controller & 2 LD PD No's, Type & Size: 12, Hitachi HUC106045CSS600 SAS rpm rev 202 & 2.5 inch 450 GB LD No's & Size: 2 & 207 GB Access Area 8 GB 16 GB 32 GB Global Access Block Size 32 KB 6 32 KB 6 32 KB 6 32 KB 6 Read Write Ratio Random/ Sequential Distribution (RAID 6) RAID6/60 (n+pq) minimum setup: n=4, actual setup: n=4 Results with L1 + L2 Cache enabled IOPS I/O (ms) Total IOPS Read IOPS Write IOPS Avg. Total Avg. Read Avg. Write L1 Hit Ratio AVG L2 Paging Size AVG L2 Cache Max Dirty Page Ratio 100% Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random Influence on NEC M-Series Disk Array Behavior & Performance 61

63 Testing Results with Cache Type Read Only (using 1 SSD of 100 GB) with 1 Controller/1 LD PD No's, Type & Size: 10, Hitachi HUC106045CSS600 SAS rpm rev 202 & 2.5 inch 450 GB LD No's & Size: 1 LD of 207 GB (RAID 5) RAID5/50 (n+p) minimum setup: n=2, actual setup: n=10 Access Area 8 GB 16 GB 32 GB Global Access Block Size 32 KB 6 32 KB 6 32 KB 6 32 KB 6 Read Write Ratio Random/ Sequential Distribution IOPS Total IOPS Read IOPS Write IOPS Results with L1 + L2 Cache enabled I/O (ms) Avg. Total Avg. Read Avg. Write L1 Hit Ratio AVG L2 Paging Size AVG L2 Cache Max Dirty Page Ratio 100% Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random % Read Random % R / 20% W Random % R / 40% W Random % Write Random Influence on NEC M-Series Disk Array Behavior & Performance 62

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