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Performance Monitoring Guide

OceanStor Dorado V3 Series V300R002

This document describes performance monitoring of storage systems, including the monitoring method, indicator planning, configuration monitoring, and problem diagnosis.
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Understanding the Pool Performance

Understanding the Pool Performance

The storage pool provides storage space for services at the upper layer. The RAID policy of the storage pool needs to be properly planned based on the real needs to enable multiple disks to work efficiently at the same time, improving I/ processing capability and data security.

Based on characteristics of SSDs, Dorado V3 uses ROW. In comparison with overwrite, full-stripe write avoids the overhead of reading disks brought by the write penalty, and also avoids frequent overwrites of parity data. After the data in the logical space is overwritten, the original data on the disk becomes garbage. The garbage data is released after being reclaimed in the background. Meanwhile, garbage reclaiming also produces extra overhead which has impact on the service performance after the reclaiming starts.

RAID combines disks into a group using certain algorithms and implements disk striping, coordinating all disks efficiently to increase the I/O processing capability of the entire system. Dorado V3 storage systems use dynamic RAID for redundancy and provide different levels of protection based on the number of parity bits in the RAID group. Table 4-3 lists the three levels of protection, RAID 5, RAID 6, and RAID-TP, provided by Dorado V3 storage systems when hot spare space is not considered.

Table 4-3 Protection levels of storage pools

Protection Level

Number of Parity Bits

Redundancy and Data Recovery Capability

Maximum Number of Allowed Faulty Disks

RAID 5

1

Relatively high. The parity data is distributed on different chunks. In each pertaining chunk group, the parity data occupies a chunk space. RAID 5 allows any one chunk to fail. However, if more than one chunk fails, this RAID level will not succeed.

1

RAID 6

2

High. The parity data is distributed on different chunks. In each pertaining chunk group, the parity data occupies two chunk spaces. RAID 6 allows two chunks to fail simultaneously. However, if three or more chunks fail, this RAID level will not succeed.

2

RAID-TP

3

High. The parity data is distributed on different chunks. In each pertaining chunk group, the parity data occupies three chunk spaces. RAID-TP allows three chunks to fail simultaneously. However, if four or more chunks fail, this RAID level will not succeed.

3

For different RAID levels, their read/write performance lies only in the RAID algorithms and thus has no big difference. The performance of RAID 5, RAID 6, and RAID-TP decreases in sequence as the redundancy level increases. For different I/O models (random/sequential, read/write), the performance is different:

  • The performance of random reads is equal to that of sequential reads.
  • The performance of sequential writes is better than that of random writes.

Select the most suitable RAID level based on site requirements. Factors including performance, space efficiency, and reliability should be taken into consideration.

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Updated: 2019-07-17

Document ID: EDOC1100049152

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