# Ceph Cluster Instability - ML110-01

**Date**: 2025-12-13  
**Status**: ⚠️ **INVESTIGATING**

---

## Issue Summary

### Symptoms
- **Ceph Monitor**: Constantly in "electing" state
- **Slow Operations**: 100+ slow operations reported
- **Manager Instability**: Ceph manager constantly restarting
- **Connection Issues**: Socket connections closing between mon0 and mon1
- **Quorum Problems**: Cluster appears to be having election issues

### Log Patterns
```
- mon.ml110-01@0(electing) e2 get_health_metrics reporting 100+ slow ops
- ENGINE Bus STOPPING/STARTING (constant restarts)
- libceph: mon0/mon1 socket closed (con state OPEN)
- Session lost, hunting for new mon
```

---

## Impact Analysis

### VMs Affected
- **Storage Type**: `ceph-fs`
- **Count**: Multiple VMs configured to use ceph-fs
- **Risk**: VM creation may fail if Ceph is unavailable

### Potential Issues
1. **VM Creation Failures**: VMs using ceph-fs may fail to create
2. **Storage Unavailable**: Ceph storage may be inaccessible
3. **Performance Degradation**: Slow operations indicate cluster stress
4. **Data Risk**: Instability could affect data integrity

---

## Root Cause Analysis

### Possible Causes
1. **Network Issues**: Connection problems between mon0 (ML110-01) and mon1 (R630-01)
2. **Quorum Loss**: Cluster may have lost quorum
3. **Resource Exhaustion**: System resources may be exhausted
4. **Configuration Issues**: Ceph configuration may be incorrect
5. **Time Sync**: Clock synchronization issues

---

## Investigation Steps

### 1. Check Ceph Cluster Health
```bash
ssh root@192.168.11.10 "ceph -s"
ssh root@192.168.11.10 "ceph health detail"
```

### 2. Verify Quorum Status
```bash
ssh root@192.168.11.10 "ceph quorum_status"
```

### 3. Check Monitor Status
```bash
ssh root@192.168.11.10 "ceph mon stat"
ssh root@192.168.11.10 "ceph mon dump"
```

### 4. Check Network Connectivity
```bash
# From ML110-01 to R630-01
ssh root@192.168.11.10 "ping -c 3 192.168.11.11"
ssh root@192.168.11.10 "telnet 192.168.11.11 6789"
```

### 5. Check System Resources
```bash
ssh root@192.168.11.10 "df -h"
ssh root@192.168.11.10 "free -h"
ssh root@192.168.11.10 "iostat -x 1 3"
```

---

## Immediate Actions

### 1. Verify Impact on VM Creation
- Check if any VMs have failed due to storage issues
- Monitor provider logs for Ceph-related errors
- Verify if VM creation is blocked

### 2. Stabilize Ceph Cluster
- Check quorum status
- Verify network connectivity
- Restart Ceph services if needed
- Check for configuration issues

### 3. Alternative Storage
- Consider using `local-lvm` for critical VMs temporarily
- Document which VMs require ceph-fs
- Plan migration if Ceph remains unstable

---

## Recommendations

### Short-term
1. **Monitor Ceph Health**: Continuously monitor cluster status
2. **Check Network**: Verify connectivity between nodes
3. **Review Logs**: Analyze Ceph logs for root cause
4. **Resource Check**: Verify system resources are adequate

### Long-term
1. **Ceph Optimization**: Optimize Ceph configuration
2. **Network Hardening**: Ensure stable network between nodes
3. **Monitoring**: Set up Ceph health monitoring
4. **Backup Strategy**: Ensure data backup strategy is in place

---

## Status

⚠️ **INVESTIGATING** - Ceph cluster instability detected, impact on VM deployment being assessed.

---

**Last Updated**: 2025-12-13  
**Status**: ⚠️ **INVESTIGATING**

