Solving Qdrant "No File Descriptors Available" Error

If you encounter the following errors in Qdrant while creating collections or indexing data:

2026-01-05T22:59:07.181456Z ERROR qdrant::actix::helpers: Error processing 
request: Service internal error: RocksDB open error: IO error: DB::Open() 
failed --- Unable to persist Options file: IO error: Unable to persist 
options.: IO error: While open a file for appending: /mnt/qdrant_data/
storage/collections/test-other-collection3/0/segments/5eb58ab2-a200-4969-
b706-42db7d9a7f10/OPTIONS-000006.dbtmp: No file descriptors available

# OR 

2026-01-05T22:22:39.870234Z ERROR qdrant::actix::helpers: Error processing 
request: Service internal error: RocksDB open error: IO error: while open 
a file for lock: /mnt/qdrant_data/storage/collections/test-other-collection
2/0/segments/f39db512-9ef3-4db4-b8c2-aeda3b1a104a/payload_index/LOCK: No 
file descriptors available

The root cause is insufficient file descriptor limits on your system.

Photo by Jan Antonin Kolar on Unsplash

Why This Happens

Qdrant uses RocksDB as its storage engine, which requires opening many files simultaneously for:

• Database segments
• Index files
• Lock files
• Write-ahead logs (WAL)
• Temporary files

When the number of open files exceeds the system limit (often default 1024), RocksDB cannot open new files and fails with “No file descriptors available.”

Solution

Step 1: Check Current Limits

First, verify your current file descriptor limits:

# Check limits for current user
ulimit -n

# Check limits for running Qdrant process
cat /proc/$(pgrep qdrant)/limits | grep "open files"

If you see 1024 or a similar low number, you need to increase it.

Step 2: Increase Limits Temporarily

For immediate testing:

# Increase limit to 65536 for current session
ulimit -n 65536

# Restart Qdrant
systemctl restart qdrant

Note: This change is temporary and will reset after reboot.

Step 3: Increase Limits Permanently

Edit /etc/security/limits.conf and add:

# For specific user (e.g., qdrant)
qdrant soft nofile 65536
qdrant hard nofile 65536

# Or for all users
* soft nofile 65536
* hard nofile 65536

Step 4: System-wide Configuration

For systemd services, edit the Qdrant service file:

# Edit service file
sudo systemctl edit qdrant

Add these lines:

[Service]
LimitNOFILE=65536

Then reload and restart:

sudo systemctl daemon-reload
sudo systemctl restart qdrant

Step 5: Verify the Changes

Check if the new limits are applied:

# For Qdrant process
cat /proc/$(pgrep qdrant)/limits | grep "open files"

# Should show something like:
# Max open files    65536    65536    files

# This is the latest open file counds
$ ls /proc/$(pgrep qdrant)/fd | wc -l
1002

# After creating one more collection
$ ls /proc/$(pgrep qdrant)/fd | wc -l
1101

Conclusion

The “No file descriptors available” error in Qdrant is a common issue that’s easily resolved by increasing file descriptor limits. Always ensure your production systems have adequate limits configured before deploying Qdrant at scale.

For more details, refer to the official Qdrant configuration guide.

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