2024年1月24日发(作者：)

Monitor the following counters to ensure the health of disks. Note that the following values represent values measured over time — notvalues that occur during a sudden spike and not values that are based on a single al Disk: % Disk Time: DataDrive This counter shows the percentage of elapsed time that the selected disk drive is busyservicing read or write requests. Monitor this counter to ensure that it remains less than two times the number of l Disk: Disk Transfers/sec This counter shows the rate at which read and write operations are performed on the disk. Use thiscounter to monitor growth trends and forecast l Disk: Disk Read Bytes/sec and Logical Disk: Disk Write Bytes/sec These counters show the rate at which bytes aretransferred from the disk during read or write l Disk: Avg. Disk Bytes/Read This counter shows the average number of bytes transferred from the disk during readoperations. This value can reflect disk latency — larger read operations can result in slightly increased l Disk: Avg. Disk Bytes/Write This counter shows the average number of bytes transferred to the disk during write value can reflect disk latency — larger write operations can result in slightly increased l Disk: Current Disk Queue Length This counter shows the number of requests outstanding on the disk at the time that theperformance data is collected. For this counter, lower values are better. Values above 2 per disk may indicate a bottleneck andshould be investigated. This means that a value of up to 8 may be acceptable for a LUN comprised of 4 disks. Bottlenecks can createa backlog that can spread beyond the current server that is accessing the disk, and result in long wait times for users. Possiblesolutions to a bottleneck are to add more disks to the RAID array, replace existing disks with faster disks, or move some data to l Disk: Avg. Disk Queue Length This counter shows the average number of both read and write requests that were queued forthe selected disk during the sample interval. The rule is that there should be two or fewer outstanding read and write requests perspindle, but this can be difficult to measure because of storage virtualization and differences in RAID levels between for larger than average disk queue lengths in combination with larger than average disk latencies. This combination canindicate that the storage array cache is being overused or that spindle sharing with other applications is affecting l Disk: Avg. Disk sec/Read This counter shows the average time, in seconds, of a read operation from the disk. On awell-tuned system, ideal values are from 1-5 milliseconds (ms) for logs (ideally 1 ms on a cached array), and 4-20 ms for data(ideally less than 10 ms). Higher latencies can occur during peak times, but if high values occur regularly, you shouldinvestigate the l Disk: Avg. Disk sec/Write This counter shows the average time, in seconds, of a write operation to the disk. On a well-tuned system, ideal values are from 1-5 ms for logs (ideally 1 ms on a cached array), and 4-20 ms for data (ideally less than 10ms). Higher latencies can occur during peak times, but if high values occur regularly, you should investigate the you are using RAID configurations with the Avg. Disk sec/Read or Avg. Disk sec/Write, use the formulas listed in the followingtable to determine the rate of input and output on the disk.

RAID levelRAID 0RAID 1RAID 5RAID 10FormulaI/Os per disk = (reads + writes) / number of disksI/Os per disk = [reads + (2 * writes)] / 2I/Os per disk = [reads + (4 * writes)] / number of disksI/Os per disk = [reads + (2 * writes)] / number of disksFor example, if you have a RAID 1 system that has two physical disks, and your counters are at the values that are shown in thefollowing table:

CounterAvg. Disk sec/ReadAvg. Disk Queue LengthValue805Logical Disk: Avg. Disk sec/Write70The I/O value per disk can be calculated as follows: (80 + (2 * 70))/2 = 110