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06.mongo

Install MongoDB v8

[!IMPORTANT]

If you use VM, set CPU type to "HOST" for this VM. (Recommended CPU is at least Intel(R) Xeon(R) CPU E2690v4)

  1. Import MongoDB repo key
sudo apt install gnupg curl
curl -fsSL https://www.mongodb.org/static/pgp/server-8.0.asc | \
   sudo gpg -o /usr/share/keyrings/mongodb-server-8.0.gpg \
   --dearmor
  1. Add MongoDB repository into your Ubuntu system.
echo "deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/mongodb-server-8.0.gpg ] https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/8.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-8.0.list
  1. Install
sudo apt update && sudo apt -y install mongodb-org
  1. Run
systemctl enable mongod --now

Update MongoDB

If you have an older version, please perform the update sequentially 6.0 > 7.0 > 8.0 Example update v7 to v8

  1. Connect to db
mongosh
  1. Check current version
db.adminCommand({ getParameter: 1, featureCompatibilityVersion: 1 });
  1. Set version
db.adminCommand({ setFeatureCompatibilityVersion: "8.0" });
  1. Check updated FCV
db.adminCommand({ getParameter: 1, featureCompatibilityVersion: 1 });

MongoDB Disk Space Reclamation (GridFS)

  1. The Issue When files are deleted from GridFS (fs.chunks), MongoDB keeps the disk space pre-allocated for future use. This creates "holes" (fragmentation) in the data files, and the OS does not see the freed space.
root@rbt:/var/lib/mongodb# ls -lah
total 73G
drwxr-xr-x  4 mongodb mongodb 4,0K апр 15 22:15 .
drwxr-xr-x 52 root    root    4,0K дек  3 11:38 ..
-rw-------  1 mongodb mongodb  32K апр 15 00:59 collection-0--6991510166517528651.wt
-rw-------  1 mongodb mongodb  73G апр 15 22:15 collection-10--6991510166517528651.wt
  1. Check Reclaimable Space
db.fs.chunks.stats().wiredTiger["block-manager"]["file bytes available for reuse"] / 1024 / 1024 / 1024

result:

rbt> db.fs.chunks.stats().wiredTiger["block-manager"]["file bytes available for reuse"] / 1024 / 1024 / 1024
| 
51.21324157714844
  1. Run Reclamation (Compact)
// 'force: true' is required if running on a Primary node
db.runCommand({ compact: 'fs.chunks', force: true })

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