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seen 14 hours ago

I currently work for MongoDB, Inc. and have a background in operations, networking and system administration. You can find me in all the usual places, but probably the most useful and relevant are listed below:

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14h
comment One of databases in MongoDB suddenly gets high lock %
Ah, I see, delving into what is evicting memory can be a bit of a dark art. I can suggest making sure you have swap configured, that you have readahead set to a sane (not too high) value. Usually the vm.swappiness and dirty settings have little effect, but that will depend on your system. If you have a system that is not seeing this behavior with the same workload, then finding the difference is key. If it is a VM, don't forget to consider the other guest VMs - a badly behaving neighbor and a struggling hypervisor can cause some weird effects
14h
comment One of databases in MongoDB suddenly gets high lock %
MongoDB is not actually in control of the freeing of memory, rather the kernel is - so if you are seeing large sections of memory being freed up, then the kernel is doing that for some reason - perhaps another process, or something that needs to be tweaked in the vm settings? Do you have some swap configured? In the end, if you are not seeing slow queries, then it would appear that there is not a lot of impact to your database at present, though it would be nice to know what is causing the impact
1d
answered One of databases in MongoDB suddenly gets high lock %
Oct
17
comment What can cause mongodb used memory to increase?
Your resident is exceeding your mapped, and that is very odd. What OS is this, and what version of MongoDB? I'd usually point you at mongomem (eng.wish.com/mongomem-memory-usage-by-collection-in-mongodb) but that's more useful when things are behaving more normally. You have resident memory going up without any hard faults, and more data in res mem than exists on disk. Still, it might be interesting to see the output
Oct
16
answered Mongostat shows 2 updates on Primaries when insert data
Oct
10
comment MongoDB failover process
No, node2 will never have enough members to automatically elect a primary because you have to have >50% of the members up and voting to do the election. No matter how you configure a 2 node setup there will always be one that does not have enough votes in a failure scenario and will require manual intervention to create a primary. Essentially, automatic failover in both directions is not possible with 2 locations, you need a 3rd location for that to happen automatically
Oct
7
comment Mongo client cannot connect on first try in bash script
Quick question: you mention using version 2.0.X but then post a 2.6.4 shell output, and that is the current version from the MongoDB repository (you should not use the packages from the Ubuntu repository as they are frozen on the older version). Can you clarify which version is actually being used for anyone trying to reproduce this?
Oct
7
answered Is it correct to use IP addresses (instead of hostnames) while configuring Mongo DB cluster? Does it cause any issues?
Oct
4
comment Socket recv() timeout on secondary nodes
One more comment - even numbers in a replica set is generally a bad idea (see stackoverflow.com/a/26179419/1148648) - you should add an arbiter to bring it up to 5
Oct
4
comment Socket recv() timeout on secondary nodes
We'll need more information to diagnose this, so it probably won't fit into a DBA Q&A and may be more suited to a thread on mongodb-user. For example: is this behind a mongos (sharded) or is it a standalone replica set? Is this Linux? Do you see any unable to allocate resource (or similar) errors in the primary/secondary logs? What are your ulimit settings? Are all the instances on separate hosts? Is your network oversubsribed, have you tested? - and that's just a start
Oct
2
answered Mongodb - see when a database was dropped
Oct
2
comment Mongodb - see when a database was dropped
The answer can also be automatically migrated when we vote to close (migration to DBA is part of the close voting options), at which point a subsequent identical question will be closed as a dupe (or this one will) - cross posting can also lead to down votes, so while it's right to point out that it belongs on DBA, it might not be the best idea to ask the question there also in the interim
Oct
1
comment At what point does the MongoDB C# driver open a connection?
Couldn't you find out with some debug print statements (or break points) and a check on current connections? Or, have the connection fail by making the mongod unavailable and see where it throws an error.
Sep
30
awarded  Explainer
Sep
25
answered Mongodb deployment best practice for dual nodes?
Sep
13
comment Understanding two types of mongodb log entries for bulk inserts
As Asya mentioned in the other posted question on this topic, this is not a simple Q&A type of problem and requires detailed troubleshooting to be anything besides guess work. Please post your question in the mongodb-user google group but be aware that this type of issue will not usually be solved straight away and will require significant information gathering, some of which Asya mentioned already
Sep
11
comment Long running query on replica worker set in mongo
That's because something/someone has sent the killOp command for that operation (not advised)
Sep
11
answered Long running query on replica worker set in mongo
Sep
11
revised Long running query on replica worker set in mongo
added 102 characters in body; edited title
Sep
11
awarded  Tag Editor