[SERVER-28361] Low cache usage on server Created: 17/Mar/17 Updated: 21/Jun/17 Resolved: 24/May/17 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | WiredTiger |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Dharshan Rangegowda | Assignee: | Mark Agarunov |
| Resolution: | Incomplete | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Operating System: | ALL |
| Participants: |
| Description |
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I have a 32 GB WT server running 3.0.8 The "bytes in cache" always seem to hover around ~1GB even though I have configured the cache size to be around ~26GB. The total data size is around 40GB. Why is the rest of the cache not being used?
The only thing special about this server is that it has a large number of dbs, around 4k. Each db has around 3 collections. |
| Comments |
| Comment by Kelsey Schubert [ 24/May/17 ] | |||
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We haven’t heard back from you for some time, so I’m going to mark this ticket as resolved. If this is still an issue for you, please provide additional information and we will reopen the ticket. Regards, | |||
| Comment by Mark Agarunov [ 07/Apr/17 ] | |||
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Hello dharshanr@scalegrid.net, Thank you for providing the data. Looking over this, the configured cache size is reported as 18GB in the diagnostic data, however above I see you have it configured for 26GB. Is it possible the diagnostic data is from a different node? Additionally, from the diagnostic data, it seems that the cache is being used as expected - there haven't been enough requests to read much data into the cache. Thanks, | |||
| Comment by Dharshan Rangegowda [ 06/Apr/17 ] | |||
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Mark - were you able to glean anything from the logs? | |||
| Comment by Dharshan Rangegowda [ 25/Mar/17 ] | |||
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Done. I have uploaded the zip file of the logs. | |||
| Comment by Mark Agarunov [ 23/Mar/17 ] | |||
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Hello dharshanr@scalegrid.net, I've generated a secure upload portal so that you can send us the files. Thanks, | |||
| Comment by Dharshan Rangegowda [ 23/Mar/17 ] | |||
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Is there a location I can upload the traces? I think they are too big to attach to the bug. | |||
| Comment by Dharshan Rangegowda [ 22/Mar/17 ] | |||
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The issue is persistent. The cache size never goes beyond 1GB. How long of a duration do you want the traces for? | |||
| Comment by Mark Agarunov [ 22/Mar/17 ] | |||
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Hello dharshanr@scalegrid.net, Thank you for the report. To better investigate this behavior, please run the following commands and provide the ss.log and iostat.log files that are created:
Please leave this running until the issue happens again so that there is a complete log. Thanks, |