12Gb SASケーブルがないため、SSDレイテンシが想定よりも高くなっています
環境
- ONTAP 9
- Data ONTAP 8
- AFF
- 12Gb SASコネクタ
問題
- 一部の状況で、All Flash FAS （AFF ）ストレージコントローラのディスクレイヤでレイテンシが想定よりも高くなることがあります。
- 想定よりも大きいレイテンシが
statitコマンドの出力またはqos statistics volume latency showコマンドの出力で確認できます。
例：
qos statistics volume latency showディスクのレイテンシを示すコマンド出力：
cluster::> qos statistics volume latency show
Workload ID Latency Network Cluster Data Disk Qos Max Qos Min NVRAM
--------------- ------ -------- -------- -------- -------- -------- -------- ---------- ----------
-total- 10.35ms 1.35ms 0ms 0us 9ms 0ms 0ms 0ms
vs1vol0 111 17.23ms 0us 0ms 603.00us 16.63ms 0ms 0ms 0ms
vol1 1234 17.76ms 0ms 0ms 150.00us 17.61ms 0ms 0ms 0ms
vol2 999 4.24ms 0us 0ms 190.00us 4.05ms 0ms 0ms 0ms
Cluster::> set -privilege diag Warning: These diagnostic commands are for use by NetApp personnel only. Do you want to continue? {y|n}: y Cluster::*> statistics start -object disk -counter "io_queued|io_pending" Statistics collection is being started for sample-id: sample_148 Cluster::*> statistics show -filter "io_queued>10|io_pending>10" Object: disk Instance: 0d.23.13 Start-time: 12/5/2022 16:48:26 End-time: 12/5/2022 16:51:58 Elapsed-time: 212s Scope: node1 Number of Constituents: 1 (complete_aggregation) Counter Value -------------------------------- -------------------------------- io_queued 19 io_pending 8 ... Cluster::*> node run -node node1 -command statit -b Cluster::*> node run -node node1 -command statit -e Disk Statistics (per second) ut% is the percent of time the disk was busy. xfers is the number of data-transfer commands issued per second. xfers = ureads + writes + cpreads + greads + gwrites chain is the average number of 4K blocks per command. usecs is the average disk round-trip time per 4K block. disk ut% xfers ureads--chain-usecs writes--chain-usecs cpreads-chain-usecs greads--chain-usecs gwrites--chain-usecs /data_aggr1/plex0/rg0: 0c.01.2 80 2510.99 1525.62 5.95 763 389.58 11.11 2682 595.79 5.22 1318 0.00 .... . 0.00 .... . 0c.01.3 81 2502.32 1510.75 5.96 758 393.43 11.27 2706 598.14 5.15 1348 0.00 .... . 0.00 .... . 0c.01.4 81 2518.91 1528.01 5.93 762 392.18 11.45 2661 598.72 5.12 1364 0.00 .... . 0.00 .... . ...