[SERVER-33537] High write IO after 3.6 upgrade Created: 28/Feb/18 Updated: 28/Feb/18 Resolved: 28/Feb/18 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Write Ops |
| Affects Version/s: | 3.6.3 |
| Fix Version/s: | None |
| Type: | Question | Priority: | Minor - P4 |
| Reporter: | Tarvi Pillessaar | Assignee: | Unassigned |
| Resolution: | Duplicate | Votes: | 0 |
| Labels: | SWKB | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Environment: |
hw: AWS c4.2xlarge conf: systemLog: net: replication: operationProfiling: |
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| Description |
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Yesterday I upgraded one of our 3.4 mongodb cluster to 3.6 (3.4.9 -> 3.6.3). When looking with iotop, I can see WTOplog.lThread is writing a lot, does it mean that 3.6 writes more oplog? Is it something that is expected or is it regression? |
| Comments |
| Comment by Bruce Lucas (Inactive) [ 28/Feb/18 ] |
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Hi Tarvi, Thanks for the data. Here's what we can see:
The rate of write operations before and after the upgrade is the same, but after the upgrade we see a much higher rate of log (journal) flushes. This is symptomatic of Thanks for your report. A fix for this is in progress and will be in a future version of 3.6. I'll close this ticket as a duplicate of Thanks, |
| Comment by Tarvi Pillessaar [ 28/Feb/18 ] |
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Hi Bruce, Thanks you for quick response. Uploaded diagnostic.data, removed older metrics files to reduce archive size, hopefully it is okay. Tarvi |
| Comment by Bruce Lucas (Inactive) [ 28/Feb/18 ] |
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Hi Tarvi, It is possible that you're encountering Thanks, |
| Comment by Tarvi Pillessaar [ 28/Feb/18 ] |
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Added 2 additional screenshots with longer timeframe. |