---
metadata:
  - name: generator
    content: Diplodoc Platform v5.52.0
alternate:
  - https://ydb.tech/docs/en/troubleshooting/performance/hardware/io-bandwidth.md?version=v25.4
  - https://ydb.tech/docs/ru/troubleshooting/performance/hardware/io-bandwidth.md?version=v25.4
  - href: en/troubleshooting/performance/hardware/io-bandwidth.md
    type: text/markdown
    title: Markdown version
  - href: ../../../llms.txt
    type: text/markdown
    title: llms.txt
sourcePath: en/core/troubleshooting/performance/hardware/io-bandwidth.md
---
> **Documentation Index:** Fetch the complete configuration index at https://ydb.tech/docs/en/llms.txt

# I/O bandwidth

A high rate of read and write operations can overwhelm the disk subsystem, leading to increased data access latencies. When the system cannot read or write data quickly enough, queries that rely on disk access will experience delays.

## Diagnostics

<!-- The include is added to allow partial overrides in overlays  -->
<!-- source: en/troubleshooting/performance/hardware/_includes/io-bandwidth.md -->
1. Open the **[Distributed Storage Overview](https://ydb.tech/docs/en/reference/observability/metrics/grafana-dashboards.md?version=v25.4)** dashboard in Grafana.

1. On the **DiskTimeAvailable and total Cost relation** chart, see if the **Total Cost** spikes cross the **DiskTimeAvailable** level.

    ![](_assets/disk-time-available--disk-cost.png)

    This chart shows the estimated total bandwidth capacity of the storage system in conventional units (green) and the total usage cost in conventional units (blue). When the total usage cost exceeds the total bandwidth capacity, the YDB storage system becomes overloaded, leading to increased latencies.

1. On the **Total burst duration** chart, check for any load spikes on the storage system. This chart displays microbursts of load on the storage system, measured in microseconds.

    ![](_assets/microbursts.png)

    {% note info %}

    This chart might show microbursts of the load that are not detected by the average usage cost in the **Cost and DiskTimeAvailable relation** chart.

    {% endnote %}
<!-- endsource: en/troubleshooting/performance/hardware/_includes/io-bandwidth.md -->

## Recommendations

Add more [storage groups](https://ydb.tech/docs/en/concepts/glossary.md?version=v25.4#storage-group) to the database.

In cases of high microburst rates, balancing the load across storage groups might help.