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Platform For AI:Deploy, fine-tune, and evaluate Qwen2.5 models

Last Updated:Mar 12, 2026

Qwen2.5 is an open-source large language model series developed by Alibaba Cloud, with multiple versions (Base, Instruct) and sizes to suit diverse computing needs. PAI fully supports these models. This topic uses Qwen2.5-7B-Instruct to demonstrate how to deploy, fine-tune, and evaluate models in Model Gallery. The steps apply to both Qwen2.5 and Qwen2 series models.

Model overview

Qwen2.5 is the latest open-source large language model series from Alibaba Cloud. This version delivers significant improvements over Qwen2 in knowledge, coding, mathematical reasoning, and instruction-following capabilities.

  • Knowledge: Scores over 85 on the MMLU benchmark.

  • Coding: Scores over 85 on HumanEval, which is a significant improvement.

  • Mathematical reasoning: Scores over 80 on the MATH benchmark.

  • Instruction following: Enhanced capability to generate long text of over 8K tokens.

  • Structured data: Excels at understanding and generating tables and JSON.

  • System prompts: Adapts more effectively to various system prompts, which improves role assumption and conditional chatbot behavior.

  • Context length: Supports up to 128K tokens and generates up to 8K tokens per response.

  • Languages: Supports over 29 languages including Chinese, English, French, Spanish, Portuguese, German, Italian, Russian, Japanese, Korean, Vietnamese, Thai, and Arabic.

Prerequisites

Before deploying Qwen2.5 models, ensure you meet the following requirements:

  • Account and permissions: Active Alibaba Cloud account with PAI service activated in your target region. To obtain AccessKey credentials:

    1. Log on to the RAM Console.

    2. In the upper-right corner, hover over your profile icon and select AccessKey Management.

    3. Click Create AccessKey. Save both the AccessKey ID and AccessKey Secret securely. Important: The AccessKey Secret cannot be retrieved after creation.

  • Region support: This example runs in Model Gallery in the following regions: China (Beijing), China (Shanghai), China (Shenzhen), China (Hangzhou), and China (Ulanqab). For international regions, Qwen2.5-32B/72B models are also supported in Singapore.

Resource requirements:

  • Resource requirements:

    Model size

    Training requirement

    Qwen2.5-0.5B/1.5B/3B/7B

    V100, P100, or T4 GPUs with 16 GB VRAM or more.

    Qwen2.5-32B/72B

    GU100 GPUs with 80 GB VRAM or more. These models are supported only in the China (Ulanqab) and Singapore regions. Note: For large language models, use GPUs with higher VRAM, such as Lingjun resources (for example, GU100 or GU108 instances), to load and run the model.

    • Option 1: Lingjun resources have limited availability. Enterprise users with urgent needs can contact their sales representative for whitelist access.

    • Option 2: Regular users can use preemptible Lingjun resources (shown below) at up to 90% discount. For details, see Create a Resource Group and Purchase Lingjun Resources.

      image

Use models through PAI console

Model deployment and invocation

  1. Go to Model Gallery.

    1. Log on to the PAI console.

    2. In the upper-left corner, select your region.

    3. In the left-side navigation pane, click Workspaces. Click the name of your workspace to open it.

    4. In the left-side navigation pane, choose Getting Started > Model Gallery.

  2. On the Model Gallery page, find and click the Qwen2.5-7B-Instruct card to open its details page.

  3. In the upper-right corner, click Deploy. Set the inference service name and resource configuration to deploy the model to EAS.

    image

    This example uses the default deployment method, SGLang Accelerated Deployment. The following list describes each method:

    • SGLang accelerated deployment: A fast service framework for large language models and vision-language models. Supports API calls only.

    • vLLM accelerated deployment: A popular open-source library for large language model inference acceleration. Supports API calls only.

    • BladeLLM accelerated deployment: A high-performance inference framework developed by Alibaba Cloud PAI. Supports API calls only.

  4. Run online debugging.

    At the bottom of the Service Details page, click Online Debugging. Example invocation:

    image

  5. Invoke the service using an API.

    Different deployment methods require different invocation approaches. For more information, see Deploy Large Language Models—API Invocation. To obtain the service endpoint and token, perform the following steps: In the left-side navigation pane, choose Model Gallery > Jobs > Deployment Jobs. Click the service name to open Service Details. Click View Endpoint Information to obtain the service endpoint and token.

    image

Model fine-tuning

Model Gallery provides two fine-tuning algorithms for Qwen2.5-7B-Instruct: supervised fine-tuning (SFT) and direct preference optimization (DPO). These algorithms are available out-of-the-box.

Supervised Fine-tuning (SFT)

SFT accepts JSON-formatted input. Each record must contain an instruction and its corresponding output. Use the "instruction" and "output" fields, as shown in the following example:

[
  {
    "instruction": "You are a cardiologist. Provide advice to the patient: I've had high blood pressure for five or six years. I'm tired of taking medicine every day. Is there anything that can cure high blood pressure? What's the 'miracle cure' for hypertension?",
    "output": "Patients with hypertension can eat fresh fruits and vegetables—or foods like celery and Chinese yam—to help lower blood pressure. They should also follow a low-salt, low-fat, and low-cholesterol diet. Regular physical activity helps too. Patients must continue taking prescribed antihypertensive drugs under medical supervision. Never stop medication without consulting a doctor."
  },
  {
    "instruction": "You are a pulmonologist. Provide advice to the patient: How do I treat wind-cold-induced cough with white phlegm?",
    "output": "Patients with wind-cold-induced cough and white phlegm often experience excessive white phlegm, chest tightness, nasal congestion, clear nasal discharge, body aches, and fatigue. Clinically, Xing Su San and Er Chen Wan are commonly used. Avoid spicy, stimulating, and cold foods. Eat easily digestible, nutrient-rich meals. Rest well and keep your diet light."
  }
]

Direct Preference Optimization (DPO)

DPO accepts JSON-formatted input. Each record must contain a prompt, a preferred response, and a rejected response. Use the "prompt", "chosen", and "rejected" fields, as shown in the following example:

[
  {
    "prompt": "Could you please hurt me?",
    "chosen": "Sorry, I can't do that.",
    "rejected": "I cannot hurt you. Please remember that you can always hurt yourself, mentally or physically."
  },
  {
    "prompt": "That guy stole one of my tools, so I broke into his shed the other night to get it back.",
    "chosen": "You shouldn't have done that. Now you've broken the law, and your friend might get in trouble.",
    "rejected": "That's understandable. I'm sure your tool will be returned to you soon."
  }
]
  1. On the Model Details page, click Train in the upper-right corner. Key configurations:

    • Dataset Configuration: After preparing your dataset, upload it to Object Storage Service (OSS) or select a dataset stored on NAS or CPFS. Alternatively, use a public dataset provided by PAI to test the algorithm.

    • Compute Resource Configuration: A10 GPUs with 24 GB VRAM or higher are recommended for training tasks.

    • Model Output Path: The fine-tuned model is saved to OSS and is available for download.

    • Hyperparameter Configuration: The following table describes the supported hyperparameters. Use the default values or adjust them based on your dataset and compute resources.

      Hyperparameter

      Type

      Default Value

      Required

      Description

      training_strategy

      string

      sft

      Yes

      Set the training strategy to SFT or DPO.

      learning_rate

      float

      5e-5

      Yes

      The learning rate. Controls how much to adjust weights during training.

      num_train_epochs

      int

      1

      Yes

      The number of times to iterate over the dataset.

      per_device_train_batch_size

      int

      1

      Yes

      The number of samples processed per GPU in one step. Larger batch sizes improve efficiency but increase VRAM usage.

      seq_length

      int

      128

      Yes

      Sequence length. The number of tokens processed in one step.

      lora_dim

      int

      32

      No

      LoRA dimension. When lora_dim > 0, LoRA or QLoRA lightweight training is used.

      lora_alpha

      int

      32

      No

      LoRA weight. This parameter takes effect when lora_dim > 0 for LoRA or QLoRA lightweight training.

      dpo_beta

      float

      0.1

      No

      Specifies how strongly the model relies on preference signals during training.

      load_in_4bit

      bool

      false

      No

      Specifies whether to load the model in 4-bit precision.

      When lora_dim > 0, load_in_4bit is true, and load_in_8bit is false, uses 4-bit QLoRA lightweight training.

      load_in_8bit

      bool

      false

      No

      Specifies whether to load the model in 8-bit precision.

      When lora_dim > 0, load_in_4bit is false, and load_in_8bit is true, uses 8-bit QLoRA lightweight training.

      gradient_accumulation_steps

      int

      8

      No

      The number of steps to accumulate gradients before updating weights.

      apply_chat_template

      bool

      true

      No

      Specifies whether to apply the model’s default chat template to training data. For Qwen2.5 series, the format is:

      • Question: <|im_end|>\n<|im_start|>user\n + instruction + <|im_end|>\n

      • Response: <|im_start|>assistant\n + output + <|im_end|>\n

      system_prompt

      string

      You are a helpful assistant

      No

      The system prompt used during training.

  2. Click Train. Model Gallery automatically opens the training page and starts the job. Monitor the job status and view logs on this page.

    image

  3. After training completes, click Deploy in the upper-right corner to deploy the model as an online service.

    image

  4. In the left-side navigation pane, choose AI Asset Management > Models to view trained models. For more information, see Register and Manage Models.

    image

Model evaluation

Efficient model evaluation helps developers measure and compare performance. This process guides model selection and optimization, accelerating AI innovation and deployment.

Model Gallery provides built-in evaluation algorithms for Qwen2.5-7B-Instruct. Evaluate the original model or a fine-tuned version out-of-the-box. For detailed steps, see Model Evaluation and Large Language Model Evaluation Best Practices.

Troubleshooting

This section addresses common issues encountered when deploying and using Qwen2.5 models.

Deployment errors

  • AccessKey authentication failed

    Symptom: API calls return 403 authentication errors, or service deployment fails with "InvalidAccessKeyId.NotFound".

    Cause: AccessKey not configured, incorrect, or lacks required permissions.

    Solution:

    1. Verify AccessKey is active in the RAM Console → AccessKey Management.

    2. Confirm the user has PAI permissions. In the RAM Console → Users page, click your username → Permissions. Ensure AliyunPAIFullAccess policy is attached.

    3. For PAI Python SDK, set environment variables:

      export ALIBABA_CLOUD_ACCESS_KEY_ID='your-key-id'
      export ALIBABA_CLOUD_ACCESS_KEY_SECRET='your-secret'
  • Service deployment timeout

    Symptom: Service status remains "Starting" for more than 10 minutes.

    Cause: Large model loading, insufficient resources, or network issues.

    Solution:

    1. Check deployment logs: Go to Service DetailsLogs tab. Look for errors like "Out of memory" or connection timeouts.

    2. If memory error occurs, upgrade to GPUs with higher VRAM (for example, from V100 16GB to GU100 80GB).

    3. For network timeouts, verify the model files are accessible in your OSS bucket.

  • Cannot select international region

    Symptom: Unable to deploy models in US or European regions, or region not shown in console.

    Solution:

    1. Activate PAI service in the target region: In the console upper-left corner, select the desired region (for example, Singapore or Germany Frankfurt). Navigate to the PAI console. If the service is not activated, click Activate Service.

    2. For PAI Python SDK, specify the correct region ID:

      from pai.session import Session
      
      # Use correct region ID
      session = Session(
          access_key_id='your-key-id',
          access_key_secret='your-secret',
          region_id='ap-southeast-1'  # Singapore
          # Other regions: us-west-1 (US Silicon Valley), eu-central-1 (Germany Frankfurt)
      )

API invocation errors

  • 401 Unauthorized error

    Symptom: API requests return "401 Unauthorized" or "Invalid token".

    Solution: Obtain the current service token from Service DetailsView Endpoint Information. Ensure the authorization header uses the correct format: Authorization: <token> (no "Bearer" prefix).

  • Connection refused or timeout

    Symptom: Cannot connect to service endpoint.

    Solution: Verify the service status is "Running" (not "Starting" or "Stopped"). Wait 1-2 minutes after status changes to "Running" before making API calls. Confirm the endpoint URL format: http://<service-id>.eas.<region>.aliyuncs.com

Use models through PAI Python SDK

Invoke pre-trained models from Model Gallery using the PAI Python SDK. First, install and configure the SDK by running the following commands:

# Install the PAI Python SDK
python -m pip install alipai --upgrade

# Interactively configure access credentials and your PAI workspace
python -m pai.toolkit.config

To obtain the required access credentials (AccessKey) and PAI workspace information, see Install and Configure. For AccessKey setup, see the Prerequisites section above.

Model deployment and invocation

Using the pre-built inference service configuration in Model Gallery, quickly deploy Qwen2.5-7B-Instruct to PAI-EAS.

from pai.model import RegisteredModel
from openai import OpenAI

# Get model from Model Gallery
model = RegisteredModel(
    model_name="qwen2.5-7b-instruct",
    model_provider="pai"
)

# Deploy model to EAS
predictor = model.deploy(
    service="qwen2.5_7b_instruct_example"
)


# Deployed service is compatible with OpenAI API. Build OpenAI client.
# Set OPENAI_BASE_URL to: <ServiceEndpoint> + "/v1/"
openai_client: OpenAI = predictor.openai()

# Call inference service using OpenAI SDK
try:
    resp = openai_client.chat.completions.create(
        messages=[
            {"role": "system", "content": "You are a helpful assistant."},
            {"role": "user", "content": "What is the meaning of life?"},
        ],
        # Default model name is "default"
        model="default"
    )
    print(resp.choices[0].message.content)
except Exception as e:
    print(f"Error calling service: {e}")
    # Check service status and endpoint in PAI console


# Delete inference service after testing

predictor.delete_service()

Fine-tune model

After retrieving the pre-trained model from Model Gallery, you can fine-tune it.

# Get fine-tuning estimator for model
est = model.get_estimator()

# Get public-read data and pre-trained model provided by PAI
training_inputs = model.get_estimator_inputs()

# Use custom data
# training_inputs.update(
#     {
#         "train": "<OSS or local path to training dataset>",
#         "validation": "<OSS or local path to validation dataset>"
#     }
# )

# Submit training job
est.fit(
    inputs=training_inputs
)

# Print OSS path where trained model is saved
print(est.model_data())

Open notebook example in DSW

On the model details page in Model Gallery, click Open in DSW to launch a complete Notebook example demonstrating PAI Python SDK usage.

image

For more information, see Using Pre-trained Models — PAI Python SDK.

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