ONTAP 9 - Per Aggregate CP
Applies to
- ONTAP 9
Answer
- ONTAP 9 has performance enhancements to lessen the impact of consistency points.
- Rather than processing a single consistency point for all aggregates at the same time (Global), ONTAP 9 has the functionality to allow each aggregate to commit CPs independently of one another.
- It is still possible for Back to Back consistency points to occur, however, the negative performance of one aggregate should not affect other aggregates.
- This is important to keep in mind when troubleshooting performance on a cluster running ONTAP 9.
- With ONTAP 9 and Per-Aggregate CP's, the CP information in sysstat has changed.
- Example (some columns removed for readability):
cluster::*> node run -node node_1 sysstat -x 1 CPU Total Net kB/s Disk kB/s CP CP_Ty CP_Ph Disk FCP kB/s iSCSI kB/s in out read write time [T--H--F--N--B--O--#--:] [n--v--p--f] util in out in out 3% 13 56 56 3300 27760 97% 1--0--0--0--0--0--0--0 0--0--0--1 65% 0 0 0 0 3% 0 55 55 30 240 11% 0--0--0--0--0--0--0--0 0--0--0--0 9% 0 0 0 0 4% 8 66 64 12 0 0% 0--0--0--0--0--0--0--0 0--0--0--0 0% 0 0 0 0 8% 0 50 50 0 12 0% 0--0--0--0--0--0--0--0 0--0--0--0 1% 0 0 0 0
- Instead of displaying individual CP's, a summary of CP's is now displayed:
CP_Ty CP_Ph
[T--H--F--N--B--O--#--:] [n--v--p--f]
- The "CP_Ty" columns now display the number of aggregates that had a CP triggered (or continuing) due to the following reasons:
CP_Ty |
Definition |
T | CP caused by timer |
H | CP caused by high water mark; the amount of modified data in the storage system's memory cache is high enough that it is ideal to start a CP to force it out to disk |
F | CP caused by full NVLog; the amount of logged data in the storage system's NVRAM pool is high enough that it is ideal to start a CP to force it out to disk |
N | CP caused by the NV Log reaching a maximum number of entries |
B | Back to back CP |
O | All other types of CP |
# | Continuation of CP from the previous interval and the storage system has determined it needs to commit the current data to disk (a watermark of some sort has been reached), so that the next CP will be of type B |
: | Continuation of CP from the previous interval |
- The
"CP_Ph"
column represents the number of aggregates in the following phases:
CP_Ph |
Definition |
n | Processing normal files |
v | Flushing modified superblock to the disk |
p | All other file processing |
f | Flushing modified data to disk |
Additional Information
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