[DOCS-6885] Add "Locked Memory Pages" ulimit note Created: 29/Dec/15  Updated: 30/Oct/23  Resolved: 01/Nov/22

Status: Closed
Project: Documentation
Component/s: manual, Server
Affects Version/s: None
Fix Version/s: Server_Docs_20231030

Type: Bug Priority: Major - P3
Reporter: Mark Benvenuto Assignee: Kay Kim (Inactive)
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
depends on SERVER-21843 secure_allocator_test fails on ppc64 Closed
Related
related to DOCS-10721 Document Locked Memory Ulimit Closed
related to SERVER-23705 Number of databases on Windows is lim... Closed
related to SERVER-23570 Make SecureAllocator a real allocator Closed
Participants:
Days since reply: 1 year, 14 weeks, 1 day ago
Epic Link: DOCSP-1769

 Description   

MonogoDB Enterprise that the ulimit for "Locked Memory Pages" is at least 16 VM pages. This means we want 64kb on Linux x86, and 1024 kb on Linux POWER. Linux x86 defaults to 64kb so this should not be an issue.

This applies to MongoDB 3.2 Enterprise and later for x86. For Power, it will be 3.3.0 and later.



 Comments   
Comment by Education Bot [ 01/Nov/22 ]

Hello! This ticket has been closed due to inactivity. If you believe this ticket is still important, please reopen it and leave a comment to explain why. Thank you!

Comment by Kevin Pulo [ 07/Apr/16 ]

In addition, in my testing I found that in Ubuntu 12.04 and 14.04:

  • Adding a line such as "limit memlock 128 128" to /etc/init/mongod.conf did not increase the amount of locked memory as I expected.
  • Adding a line "limit -l 128" immediately prior to the "exec start-stop-daemon ..." line in that file also did not increase the mongod's memlock ulimit as I expected it to.
  • Increasing the memlock ulimit for the mongodb user in /etc/security/limits.conf also did not succeed.
  • However, bizarrely, adding "limit -l 128" to /etc/default/mongod" (which is sourced by /etc/init/mongod.conf) did cause the mongod memlock ulimit to be adjusted.
  • EDIT: I got bitten by this stupidity in upstart. If I do "stop mongod" and "start mongod", then it picks up the adjusted "limit memlock" line as it should.

Se still likely need to investigate the most appropriate way of adjusting the memlock ulimit for each Linux distribution.

Comment by Kevin Pulo [ 07/Apr/16 ]

Although the minimum recommendation for the memlock ulimit should be 16 VM pages, and 3.2.5+ will issue a startupWarning if started with less than that, currently the Encryption At Rest feature requires 16kb + 4kb * number_of_dbs. SERVER-23570 should lower this requirement considerably.

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