Free tools Windows power users keep installed
One-click scans. No signup required.
Install a fault-tolerant ZooKeeper ensemble on three separate Ubuntu VPS servers, give every node the same server list, assign each host a unique myid, and restrict ports with private firewall rules. The procedure below covers Java, directory layout, zoo.cfg, startup, leader-election checks, failure testing, and the storage and monitoring work required for production.
Need a server to try this on? Antihost offers Linux VPS plans with NVMe storage, full root access and a 14-day free trial.
What you are building
ZooKeeper is a coordination service that stores small, strongly ordered pieces of state for distributed applications. A production deployment is an ensemble: several ZooKeeper servers that replicate state and elect one leader. Clients can connect to any healthy server, while the servers communicate over separate quorum and leader-election channels.
As an Amazon Associate I earn from qualifying purchases.
“For reliable ZooKeeper service, you should deploy ZooKeeper in a cluster known as an ensemble.” — Apache ZooKeeper Administrator’s Guide
Use three separate VPS instances for the baseline deployment. A majority must remain available for the ensemble to accept writes, so an odd number of servers gives more fault tolerance for the same approximate number of machines.
#1 Best Overall
- BLUE LIGHT BLOCKING GLASSES: Our blue light glasses for women boast UV400 protection, blocking harmful blue rays from computer screens. With these bluelight glasses women, you can enjoy gaming, reading, or watching TV with no worries of eye strain.
- EYE RELIEF: Our blue light glasses are engineered to reduce blurry vision or strain caused by prolonged screen time. These womens blue light glasses aid in better sleep by preventing blue light from disrupting your natural sleep cycle, helping you fall asleep faster and enjoy a more restful night's sleep, making them the perfect christmas present.
- COMFORTABLE: Crafted from durable material, our trendy blue light glasses for woman or blue light glasses men ensure long-lasting comfort. The high-transmittance lenses accessories, gamer gifts for men, help keep your eyes relaxed. Perfect stocking stuffers, gifts for gamers men, christmas gifts for men, halloween costumes.
- LIGHTWEIGHT: These clear blue light glasses feature a lightweight frame, meaning they’ll stay comfy for long-term wear. Perfect as blue blockers glasses for women or mens blue light glasses, these non-prescription fake glasses for men can be worn throughout the day. The blue light blocking glasses women feature polycarbonate HD lenses, which are anti-reflective and restore true color.
- WORRY-FREE PURCHASE: If you experience any issues, our support team is ready to assist you quickly. These are the perfect costume glasses for cosplay dressing up.
| Ensemble size | Majority required | Failures tolerated while retaining a majority |
|---|---|---|
| 3 | 2 | 1 |
| 4 | 3 | 1 |
| 5 | 3 | 2 |
Four servers do not tolerate more failures than three: both lose service after two failures. Five servers can lose two machines, which is why odd-sized ensembles are normally preferred.
Example topology
The examples use three hosts with stable private DNS names or private addresses:
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
- zk1 — server ID 1
- zk2 — server ID 2
- zk3 — server ID 3
Every host must be able to resolve and reach all three names. Do not build the ensemble from public addresses when the VPS provider offers private networking. If private DNS is unavailable, create consistent internal host records or use fixed private addresses in every configuration file.
Requirements before installation
Separate machines and failure domains
Provision three Ubuntu VPS instances that are independently reachable. Placing all three virtual machines on one physical host or one storage device can remove the failure independence that the ensemble is supposed to provide. When your provider offers availability zones or separate hosts, distribute the instances across them without increasing network latency beyond what your application can tolerate.
Network and storage requirements
- Private connectivity between every pair of ZooKeeper servers.
- TCP 2181 for trusted application clients.
- TCP 2888 for server-to-server quorum traffic.
- TCP 3888 for leader-election traffic.
- Persistent storage for snapshots and transaction logs.
- Disk latency and IOPS that remain predictable under load.
- Provider snapshots or another backup mechanism compatible with your recovery objective.
IPv4 and IPv6 behavior, monitoring, regional availability, and firewall controls differ by VPS provider. Confirm those details before deploying; a low-cost plan that lacks private networking or persistent disks is not equivalent to a three-node production ensemble.
Choose and pin a ZooKeeper release
Download the selected Apache ZooKeeper binary from Apache’s download infrastructure. Record the exact release in your deployment notes instead of following a moving filename. Verify the published checksum or signature before unpacking; do not treat a successful download as proof that the archive is authentic.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Rank #2
- WINDEX GAMING WIPES: effortlessly clean all your gaming gear and gaming electronics in one easy step with our new Windex Gaming Wipes
- AMMONIA FREE: our ammonia-free formula is safe to use on all of your favorite gaming equipment like consoles, headsets, controllers, screens, keyboards, and more
- PRE-MOISTENED WIPES: each wipe instantly removes dust, dirt, and stubborn smudges and fingerprints leaving a streak-free shine
- ANTI-STATIC: great for cleaning and wiping down your gaming gear and electronics leaving behind no visible residue
- COMPACT RESEALABLE PACKAGE: store your pack of Windex Gaming Wipes anywhere in your home for whenever a quick and easy wipedown is needed
Prepare each Ubuntu VPS
Perform the following preparation on zk1, zk2, and zk3. Run administrative commands with sudo, and substitute each host’s own name and private address where appropriate.
- Apply security updates. Run
sudo apt update, then install the current security and distribution updates supported by your Ubuntu release. Reboot if the kernel or core libraries require it, and verify that the host returns with its private network intact. - Install a supported Java runtime. ZooKeeper requires Java. Use the OpenJDK runtime supported by the Ubuntu and ZooKeeper releases you selected; package names and supported Java versions change between Ubuntu releases. After installation, run
java -versionand record the result with the ZooKeeper version. - Create a dedicated account. Create a system user and group named
zookeeper. Do not run the service as root. A typical Debian-family command issudo adduser --system --group --home /var/lib/zookeeper zookeeper; if your Ubuntu image uses a different account-management policy, create an equivalent non-login service account. - Create separate paths. Keep the installation, configuration, data, transaction-log, and application-log locations distinct. For example, create
/opt/zookeeperfor the unpacked distribution,/var/lib/zookeeperfor snapshots and state,/var/lib/zookeeper-logfor the transaction log, and/var/log/zookeeperfor logs. Set ownership so the service account can write only where it needs to. - Install the verified archive. Unpack the checksum-verified release under
/opt, place its configuration in the distribution’s configuration directory, and keep the executable files owned by root where practical. Ensure thezookeeperaccount can read the installation and write the configured data and log directories.
The exact Java package command and archive directory name depend on the Ubuntu and ZooKeeper releases. Pin both versions in your operations notes so a later administrator can reproduce the installation.
Configure the ensemble identically
Create the same zoo.cfg on all three hosts. The server list, ports, timing values, and directory paths must match. A practical baseline is:
tickTime=2000
dataDir=/var/lib/zookeeper
dataLogDir=/var/lib/zookeeper-log
clientPort=2181
initLimit=5
syncLimit=2
server.1=zk1:2888:3888
server.2=zk2:2888:3888
server.3=zk3:2888:3888| Property | Purpose | Baseline shown |
|---|---|---|
tickTime |
Basic ZooKeeper time unit, in milliseconds. | 2000 ms |
dataDir |
Stores snapshots and transaction updates when no separate transaction-log directory is used. | /var/lib/zookeeper |
dataLogDir |
Places transaction logs on a separate path, allowing you to use faster or less-busy storage. | /var/lib/zookeeper-log |
clientPort |
TCP listener used by application clients and the command-line client. | 2181 |
initLimit |
Controls the time allowed for a follower to connect and synchronize during startup, measured in tickTime units. |
5 |
syncLimit |
Controls the heartbeat and synchronization tolerance between a leader and follower, measured in tickTime units. |
2 |
server.id |
Defines each ensemble member as host:quorumPort:electionPort. |
2888:3888 |
The values above are configuration guidance from Apache’s getting-started and administrator documentation, not a performance guarantee. Slow disks, high network latency, or long restart times may require different timing values after load testing.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsWhy the complete server list matters
Each node must contain all three server.id entries, in the same form and with the same IDs. Do not give zk1 a list containing only itself, and do not use one host’s public name while another node uses its private name. A mismatch can prevent quorum formation or make clients discover different ensembles.
Create the myid file
ZooKeeper maps the numeric server ID in zoo.cfg to a file named myid in the configured dataDir. The file must contain exactly one number and no extra words:
Rank #3
- Ergonomic & Adjustable Design: Fight "text neck" and improve your posture. Designed for comfort, it offers an adjustable height (7.1in-8.5in) (1.4in adjustable range) and angle (5°-85°) Please note: cell phone stand is only 9 inches tall—the length of a standard pencil
- Without blocking subtitles Perfect for office desk Tiktok Face Time Zoom video—this is the ultimate kitchen desk essential for phones! Perfect viewing experience while reducing neck back strain, A must-have for gamers streamers desk, and anyone who values both style and support!
- Sleek & Stable Design fits Otterbox Case: Say goodbye to bent cables, tangles, and tip-overs! LISEN’s stylish adjustable desk phone holder features a built-in charging hole and smart cable management, keeping your phone secure and your workspace clutter-free cool gadgets for men
- ANTI-SLIP DESIGN free hands: The under 10.00 items easy gadgets back and the bottom of this kitchen essentials for women are fully covered by anti-skid silicone, which LISEN stand up desk decor can provide maximum protection device from any scratches and slides
- Your Perfect Viewing Companion:If your product arrives damaged or breaks within 365 days, reach out to LISEN for a quick and hassle-free solution. Struggling with assembly, like tightening the screw? We’ve got your back! Your experience matters to us. (Product including: phone Holder stand*1, screw*1, hexagon screwdriver*1, specification*1)
| Host | File | Exact content |
|---|---|---|
| zk1 | /var/lib/zookeeper/myid |
1 |
| zk2 | /var/lib/zookeeper/myid |
2 |
| zk3 | /var/lib/zookeeper/myid |
3 |
On each machine, create the file with the ID assigned to that machine, then set ownership and restrictive permissions. For example, on zk1:
printf '1n' | sudo tee /var/lib/zookeeper/myid
sudo chown zookeeper:zookeeper /var/lib/zookeeper/myid
sudo chmod 640 /var/lib/zookeeper/myidUse 2 and 3 in the first command on zk2 and zk3. Check the result with sudo cat /var/lib/zookeeper/myid before starting the service. A copied data directory with the wrong ID is a common cause of failed elections.
Lock down the firewall
“It is thus recommended to deploy ZooKeeper behind a firewall.” — Apache ZooKeeper Administrator’s Guide
Apply rules at both the VPS provider’s network firewall and the Ubuntu host firewall when both are available:
- Permit TCP 2181 only from the application subnets or administration hosts that genuinely need ZooKeeper.
- Permit TCP 2888 only between the private addresses of zk1, zk2, and zk3.
- Permit TCP 3888 only between those same three private addresses.
- Deny unsolicited access to all three ports from the public internet.
Cloud-firewall syntax varies by provider, so create source-restricted rules rather than copying a provider-specific command into another environment. Review the effective rules with the provider’s console and with Ubuntu’s firewall status command. If clients must connect from outside the private network, use a private overlay or VPN and restrict source addresses tightly. Then enable the authentication and TLS features supported by the exact ZooKeeper release you installed; a public listener protected only by an IP rule is not an adequate internet-facing design.
Start the three servers
Start the members after their configuration, ownership, name resolution, and firewall rules are in place. Start them one at a time so that errors are easy to associate with a host.
Rank #4
- Easy Installation: Our gaming lights have been designed to enhance your entertainment experience. Simply position the led light bar next to your TV or game console to create a game room environment with ease. They come with USB power and a 60 inch cord for direct mounting and mobility
- Audio Syncing & Extensive Mode: The built-in high-sensitivity music sensor allows you to sync the TV led lights to your favorite music. Lights react and move to the beat of music, film and game audio, creating an incredible immersive sound and light experience – and all without the need for an additional hub. You can choose from 64+ patterns, including strobe, illusion, jump, energy, gradient, running, chasing, fluttering mode etc. Each mode can be applied to different scenes
- 64+ Chasing IC+RGB & W Effect: The independent control design of IC+RGB and white all-in-one multifunctional rgbw led bar lights monitor backlight allows you to easily switch the led lights for desk between IC+RGB and white to enjoy a variety of lighting effects, you can choose white lighting mode with high brightness for better illumination when working, etc. Choose IC+RGB lighting mode when you need to create an entertaining atmosphere for the light show, 16 million colours of Color changing rgb light bar let you dance to the beat and create a dynamic party atmosphere
- Dynamic and Dimmable Lights: 1%-full brightness free brightness adjustment gives you the flexibility to adjust dimmable led light bar for room decorations or a variety of occasions
- USB Powered: USB light bars for room can be powered by powernank, usb charger, TV, Monitor, laptop PC mainframe, making behind TV led lighting bar easy to install in any location.TV led lights are powered by the TV usb interface / PC mainframe, can be turned on/off synchronously with TV / PC
- On each node, confirm that
java -version,sudo cat /var/lib/zookeeper/myid, and the localzoo.cfgare correct. - Run the distribution launcher as the service account, for example
sudo -u zookeeper /opt/zookeeper/bin/zkServer.sh start. Set the distribution’s log-directory environment variable if required so logs go to/var/log/zookeeperrather than an unwritable installation directory. - Check the launcher output and the ZooKeeper log on that host. A process can start before it has joined a quorum, so do not treat a returned shell prompt as a health result.
- Repeat the start command on the other two nodes. Allow enough time for DNS resolution, TCP connection establishment, synchronization, and leader election.
The official getting-started guide documents bin/zkServer.sh start and distinguishes standalone operation from replicated operation. Use the equivalent path if you installed the binaries elsewhere.
Verify quorum, leader election, and client operations
Check listeners and logs
From an allowed administration host, verify that each server listens on its intended interfaces and ports with the operating system’s socket tool, such as ss -ltn. Confirm that 2181 is reachable from an approved client network and that 2888 and 3888 are reachable only across the private server network.
Read the ZooKeeper logs on all three hosts. A healthy startup should show that one member is acting as leader and the other members are following it. If a server remains in a looking state, inspect name resolution, private routes, firewall rules, the myid value, and whether every node has the identical server list.
Run a harmless CLI test
From a trusted client host, connect with the command-line client supplied by the same ZooKeeper distribution:
/opt/zookeeper/bin/zkCli.sh -server zk1:2181In the interactive shell, use a disposable znode for a read/write check, then remove it:
create /install-check ready
get /install-check
delete /install-checkRepeat the connection through zk2 and zk3, or provide a comma-separated server list in the syntax supported by your release. A successful TCP connection alone is insufficient: the read and write must complete, and the logs must show that all expected members are connected.
Best Value
- Compatible with Wide Screens - To ensure compatibility with the dual monitor mount, your each monitor must meet three conditions at the same time: First, computer screens size range: 13 to 32 inches. Second, screen weight range: 4.4 to 19.8 lbs. Third, the back of the monitor screen must have VESA mounting holes with a pitch of 75x75mm or 100x100mm.
- Regarding the compatibility with desks - Your desk must meet three conditions at the same time: First, desk material: Only wooden desks are recommended, plastic or glass desks cannot be used. Second, desk thickness range: 0.59" - 3.54". Third, the bottom of the desk should not have any cross beams or panels, as this will interfere with installation. We recommend carefully checking that your desk and monitors meets all above conditions before purchasing.
- Dual C-Clamp Hold - Worried your dual monitors might wobble or slip? Our upgraded base uses a larger platform plus a dual C-clamp structure to lock the dual monitor arm firmly to your desk. Each arm safely keeps your screens steady while you type, click and game—no shaking, no sliding, just a clean and secure setup you can trust every day. It also provides Grommet Mounting installation choice, both options ensure stable and secure fixation for your 0.59" - 3.54" desk.
- Full-Motion Adjustment For Comfortable View - Pull the screen closer when you’re deep in a spreadsheet, push it back to watch videos, or rotate to portrait for coding — moving everything smoothly with just one hand. The monitor stand offers +85°/-50° tilt, ±90° swivel and 360° rotation. Raise your monitor up to 15.75″ to support a healthy sitting posture. Whether you’re working from home, gaming through the night, or switching between video calls and documents, getting the screens to your natural line of sight helps relieve neck, shoulder and back strain so you can stay focused longer with less fatigue.
- Keep Your Desk Organized: By lifting both screens off the desktop, this dual monitor stand opens up valuable space for your keyboard, notebook, docking station or a simple, clutter-free work area. Built-in cable management guides wires along the arms, keeping cords out of sight and out of the way. Enjoy a tidy, modern workstation that looks as good as it feels to use.
ZooKeeper releases differ in which four-letter administrative commands and monitoring endpoints are enabled by default. Use the monitoring and CLI instructions for the exact release rather than enabling diagnostic commands broadly on a public interface.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallPerform a controlled one-node failure test
During a maintenance window, stop one member with the distribution’s stop command, then perform the disposable CLI read/write test again. A three-node ensemble should continue serving with the remaining two members if they are synchronized and network-connected. Restart the stopped member, wait for it to rejoin and catch up, and confirm in the logs that the ensemble returns to three connected members. Record the observed recovery time; do not advertise failover behavior until you have tested it in your own network and storage conditions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Storage, JVM, and operating practices
Protect the transaction log
Transaction-log placement is performance-critical. Put dataLogDir on fast, reliable storage that is not saturated by unrelated workloads. A busy or inconsistent disk can increase commit latency and make followers fall behind even when CPU usage is low.
Size the Java heap conservatively
Do not allocate nearly all VPS memory to Java. ZooKeeper also needs operating-system memory and filesystem cache, and swapping severely degrades performance. Start with a conservative heap, observe the workload, and use load testing to determine the final value. Alert before the host reaches swap pressure rather than trying to recover after swapping begins.
Back up and monitor
- Use persistent volumes rather than ephemeral instance storage.
- Schedule snapshots or backups that match the recovery point and recovery time objectives for your application.
- Follow the selected release’s snapshot and restore documentation before automating restoration.
- Rotate logs and verify that rotation does not remove files still needed for diagnosis.
- Monitor disk capacity, transaction-log growth, JVM heap, request latency, process availability, and quorum membership.
- Alert on loss of a follower, loss of quorum, repeated leader elections, and failed client requests.
Backups do not replace quorum. A backup is useful only if you have tested how to restore it and understand which application state must be recreated alongside ZooKeeper data.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Plan upgrades and maintenance
Pin the binary and Java versions in change records. Before upgrading, read the compatibility and rolling-upgrade guidance for that ZooKeeper release. Maintain a majority during planned work, upgrade one member at a time, and verify that it rejoins before touching the next member. Never remove two members of a three-node ensemble simultaneously.
Choosing VPS infrastructure for this deployment
Compare infrastructure on operational properties rather than headline CPU or monthly price. Use this checklist when evaluating a VPS plan:
| Axis | What to confirm | Why it affects ZooKeeper |
|---|---|---|
| Private networking | All three instances can reach one another on stable private addresses. | Quorum and election traffic should not traverse the public internet. |
| Disk behavior | Persistent volumes with predictable latency and documented IOPS. | Transaction-log latency directly affects commit performance. |
| Failure separation | Independent hosts or availability zones are available. | A single underlying failure should not remove the majority. |
| Firewall controls | Rules can restrict sources and ports separately. | Client, quorum, and election traffic have different trust boundaries. |
| Backups | Snapshots and exports can be scheduled and restored. | Recovery planning requires more than a running process. |
| Addressing | Stable private DNS or fixed private IPs, with known IPv4/IPv6 behavior. | Every node must resolve the same complete server list. |
| Monitoring | Host and network metrics plus alert delivery. | A running process can still be outside a healthy quorum. |
| Regional availability | Locations and zones match your latency and resilience requirements. | Excessive latency can cause synchronization and election problems. |
Three separately reachable instances with persistent storage and restrictive firewall rules are the minimum practical shape for this guide. A single-host arrangement may be cheaper, but it does not provide the failure independence implied by an ensemble.
Troubleshooting common failures
| Symptom | Likely cause | Action |
|---|---|---|
| Server remains in looking state | Wrong myid, incomplete server list, blocked 2888/3888, or failed name resolution. |
Compare zoo.cfg byte-for-byte, verify the local ID, resolve every hostname from every node, and inspect private firewall rules. |
| Clients receive connection refused on 2181 | Process is stopped, listening only on another interface, or blocked by a client firewall. | Check the process and listening sockets locally, then test from an allowed client address and review source restrictions. |
| Process starts but no leader appears | Fewer than a majority of configured servers are reachable or members disagree about IDs. | Restore connectivity to at least two of three nodes, correct IDs, and read all three logs for election errors. |
| Writes are slow while CPU is low | Transaction log is on busy or high-latency storage, or the host is swapping. | Move the log to reliable fast storage, inspect disk latency and swap activity, and reduce heap pressure. |
| Follower repeatedly disconnects | Unstable private network, overloaded disk, or timing values too aggressive for startup conditions. | Measure network and disk behavior, correct infrastructure issues, and adjust timing only after testing. |
| One node shows different data | Configuration mismatch, an incorrect data directory, or an unsafe restore. | Stop and isolate the affected member, preserve logs, compare paths and configuration, and follow the release’s recovery procedure rather than deleting state casually. |
| Disk fills unexpectedly | Unrotated logs, growing snapshots, or insufficient capacity planning. | Configure rotation and alerts, inspect transaction-log growth, and expand persistent storage before the filesystem reaches capacity. |
Production readiness checklist
- Three or more separate VPS instances are deployed, preferably in independent failure domains.
- All nodes run a pinned, verified Apache ZooKeeper release and a supported Java runtime.
- The same complete
zoo.cfgis present on every node. - Each
dataDircontains the correct single-numbermyid. - TCP 2181 is limited to trusted clients; TCP 2888 and 3888 are limited to the ensemble.
- Transaction logs use persistent, reliable storage with adequate latency and capacity.
- Heap sizing leaves room for the operating system and filesystem cache; swap alerts are active.
- Backups, snapshots, log rotation, and restore procedures are documented and tested.
- Monitoring detects quorum loss, leader-election loops, latency, heap pressure, disk exhaustion, and failed client requests.
- A controlled one-node stop and restart has demonstrated that the remaining majority serves requests and that the recovered member rejoins.
Final guidance
A correct three-node configuration is only the starting point. ZooKeeper’s availability depends on majority, its performance depends heavily on transaction-log storage and memory headroom, and its security depends on keeping client and inter-server ports private. Treat identical configuration, unique myid files, restrictive firewall rules, tested backups, and an observed failure test as release criteria—not optional cleanup after installation.
Recommended Free Tools
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
