AIX Power System Assessment

Transcription

1 When conducting an AIX Power system assessment, we look at how CPU, Memory and Disk I/O are being consumed. This can assist in determining whether or not the system is sufficiently sized. An undersized system can create bottlenecks and lead to performance issues. An over-sized system will waste system resources that could be utilized for other workloads. In addition systems that have CPU resources that are not utilized can potentially reduce their software licensing cost by removing them from the Logical Partition. Innovative Information Solutions will review your system configurations and conduct a deep dive into the system performance characteristics. Referenced within this paper is a real world assessment that was conducted for one of our AIX customers. This assessment was conducted over a 3 day period in which we gathered information from their systems. One of the most important utilized resources in the power system is your CPU Utilization. Therefore, we reviewed the CPU Load on the system using our tools. This is the physical CPU analysis of their Oracle Production system. This assessment showed that there were two time periods during the day that the system was heavily consuming processor cycles. It was determined that this was when a batch export and their daily backups were being done. Outside of those two windows, the CPU was much lower. Note that the total CPU allocated to this Logical Partition is 8 CPU Cores. This would mean from an Oracle perspective they would be paying for 8 Cores of Oracle. The analysis clearly shows that they are not using 8 Cores at any point during the day and this is an average days graph showing the typical peak per day based upon 3 days of data. Figure 1 PCPU Total Oracle Production 8/21/ User Sys Wait :43 1:25 2:7 2:49 3:31 4:13 4:55 5:37 6:19 7:1 7:43 8:25 9:7 9:49 1:32 11:14 11:56 12:38 13:2 14:2 14:44 15:26 16:8 16:5 17:32 18:56 19:38 2:2 21:2 21:44 22:26 23:8 23:5 1

2 CPU Entitlement is the Logical Partitions available CPU, and in an uncapped partition this variable would equal the number of licensed CPU they would be required to purchase for software compliance. This system was running in un-capped mode with a CPU entitlement of 8 Cores. Since the system is running in Uncapped mode, the end user must be very cautious about software compliance and if their maximum virtual CPUs is higher than their entitled CPUs, they can exceed their entitled capacity if the cores are available and if the system call for them. The process of gaining or releasing cores on the power system is called CPU (processor) Folding. During our assessment period, processor folding is one of the variables we analysis to analyzed their performance. An overabundant amount of processor folding would indicate either an undersized or oversized Logical Partition. If the system in this example had a Maximum Virtual Processor setting of 1 and the CPU was available, they could potentially utilized 1 cores on this system. In some cases, software licenses will require you to license all the cores on the managed system if you are running in Uncapped mode, therefore it is a good idea to conduct an analysis to determine how much CPU you need on the system and run the virtual machine in capped mode giving you the amount of CPU you need to conduct all your work loads. You will also see that during the day there is a lot of CPU folding taking place (Green lines in graph). This is a good thing for two reasons: 1. This will free up these CPUs to be utilized on other virtual machines making for a more efficient system and not wasting these CPU cycles. 2. Running the load on fewer cores means that the memory segments allocated to the jobs will cache better meaning that data will load faster into the CPU registers. This snapshot is for a 24-hour period, but we ran the analysis for 3 days and only a few very rare times did the CPU peak at over 6 CPU and it never made it to the allocated number of CPUs of Physical CPU vs Entitlement Oracle Production 8/21/217 :53 1:45 2:37 3:29 4:21 5:13 6:5 6:57 7:49 8:41 9:33 1:26 11:18 12:1 13:2 13:54 14:46 15:38 16:3 17:22 19:6 19:58 22:34 23:26 PhysicalCPU entitled Unfolded VPs 2

3 Another variable we look at when conducting an AIX assessment in system memory. The majority of AIX systems are used for larger database systems. These database structures will tend to utilize a large amount of system memory as filesystem cache space. Therefore, on a system that is been running for a long time it will frequently show memory as 1% utilized. There is a lot of tuning variable that can be modified to change how the system will use this cached memory. In the case with Oracle, the filesystem can be mounted with the cache turned off. This can be beneficial since the database can cache this information within its own pinned memory segments. In the case of this sample assessment we remove the filesystem cache from the memory utilization showing that the system is has plenty of head room memory wise Memory Used Oracle Production 8/21/217 :53 1:45 2:37 3:29 4:21 5:13 6:5 6:57 7:49 8:41 9:33 1:25 11:17 12:9 13:1 13:54 14:46 15:38 16:3 17:22 19:6 19:58 22:34 23:26 System% Process% 3

4 The last major variable that we look into is the system storage. Storage is analyzed in two ways: the utilization of the storage and the performance of the storage. In order to get the filesystem utilization, we review the volume group utilization and the filesystem space utilized. In this case the filesystem utilization can change throughout a given day due to database and archive logs being generated backed up and then deleted after their backup is completed. In the attached example, you can see that there is one filesystem (/u2) which is 9% utilized and normally this would be a concern. However, in this case this filesystem is over 3TB in size and is growing at a very slow rate. Over a long-term collection of data for this client, we calculated they would have enough space in the file system for the next two years. In this output you can also see that the /u3 filesystem grows throughout the day peaking at about 55% and then dropping back down to 2%. This is the Oracle logging space which grows and then gets pruned back during the day. JFS File space %Used Oracle Production 8/21/ / /home /usr /var /tmp /admin /opt /u2 /u1 /u3 /exports Avg. WAvg. Max. 4

5 The I/O performance of the system is also measured as part of this assessment. We look at the physical Read and Writes per second of each disk along with the over I/O per second that the system is undergoing. In figure 1 below you can see that the disk reads are peaking at 12, and the disk writes are peaking at 22,. This gives them a read write ratio of 85 percent reads to 15 percent writes. The majority of the writes occurred during the batch loads in the morning and the backups in the evening. A large majority of the backup IOPS were eliminated with the implementation of IBM s Flash Copy after which the filesystems to be backed up were mounted onto an alternative Logical Partition and backed up from an alternative system. This reduced the strain on the system and effectively removed their backup window from hours down to seconds. Figure 1 Disk Read KB/s Oracle Production 8/21/217 hdisk6 hdisk7 hdisk9 hdisk1 hdisk11 hdisk2 hdisk18 hdisk1 hdisk4 hdisk17 hdisk8 Thousands :53 1:45 2:37 3:29 4:21 5:13 6:5 6:57 7:49 8:41 9:33 1:25 11:17 12:9 13:1 13:54 14:46 15:38 16:3 17:22 19:6 19:58 22:34 23: Disk IO Writes per second Oracle Production 8/21/217 hdisk7 hdisk6 hdisk9 hdisk17 hdisk18 hdisk2 hdisk1 hdisk4 hdisk11 hdisk1 hdisk8 :49 1:37 2:25 3:13 4:1 4:49 5:37 6:25 7:13 8:1 8:49 9:37 1:25 11:13 12:1 12:49 13:37 14:26 15:14 16:2 16:5 17:38 18:26 19:14 2:2 21:38 22:26 23:14 5

6 Follow up analysis Post system modifications to CPU entitlement Modifications were made to the Entitled physical cores on the system and were capped at 6 CPUs. The system was then analyzed for another 3-day period showing the performance of the system during this time period. This change still left enough headroom to account for high system utilization during peak periods. This also allowed them to create a new LPAR that they could no use with flash copy to mount their flash copy LUNs to and perform system backups without utilizing their production CPU, Memory or Storage IOPS Physical CPU vs Entitlement Oracle Production 1/16/217 :51 1:41 2:31 3:21 4:11 5:1 5:51 6:41 7:31 8:21 9:11 1:1 1:51 11:41 12:31 13:21 14:11 15:1 15:51 16:41 17:31 18:21 19:11 2:2 2:52 22:32 23:22 PhysicalCPU entitled Unfolded VPs Call for your free AIX assessment today!