> ## Documentation Index > Fetch the complete documentation index at: https://docs.sailresearch.com/llms.txt > Use this file to discover all available pages before exploring further. # Mount a volume on a running Sailbox > Add a volume at an empty absolute path without restarting the Sailbox. Return after the mount is applied. Identical retries are safe. A timeout can leave a recorded attachment; retry the same request. Existing mounts cannot be removed or replaced. Older Sailboxes require an explicit upgrade. Existing containers need mount propagation to see this new mount. ## OpenAPI ````yaml /sailbox-openapi.json put /sailboxes/{sailbox_id}/volume-mounts openapi: 3.1.0 info: title: Sail Sailbox API version: '2026-09-07' description: >- Create and operate Sailboxes over HTTP. Sailboxes are fast-booting virtual machines that you can pause, resume, and checkpoint. Run commands, stream files, manage lifecycle and networking, and inspect usage. Turning on SSH and building an image still require an SDK or the CLI. See the [HTTP API guide](/sailboxes-http-api). servers: - url: https://sailbox-api.sailresearch.com/v1 security: - BearerAuth: [] tags: - name: Apps description: Groups that own Sailboxes. One app per workload. - name: Lifecycle description: >- A Sailbox's whole life: create it, watch it, stop and start it, terminate it. - name: Checkpoints description: Save a Sailbox to start from later, and copy a running one. - name: Exec description: Run commands and control their standard input and terminals. - name: Files description: Stream regular files into and out of a Sailbox. - name: Networking description: >- Publish ports, serve them on hostnames you own, and identify a Sailbox to other Sailboxes. - name: Secrets description: >- Organization values that egress policy rules can add to matching requests. Sail never returns a stored value. - name: Egress policies description: >- What a Sailbox may connect to, and what happens to the HTTPS requests it sends. - name: Volumes description: >- Shared storage that outlives any one Sailbox. Alpha: these endpoints can still change. - name: SSH access description: Certificates for connecting to a Sailbox with `ssh`. - name: Usage description: Resource usage and spend. - name: Identity description: Who your API key belongs to. paths: /sailboxes/{sailbox_id}/volume-mounts: put: tags: - Volumes summary: Mount a volume on a running Sailbox description: >- Add a volume at an empty absolute path without restarting the Sailbox. Return after the mount is applied. Identical retries are safe. A timeout can leave a recorded attachment; retry the same request. Existing mounts cannot be removed or replaced. Older Sailboxes require an explicit upgrade. Existing containers need mount propagation to see this new mount. operationId: mountSailboxVolume parameters: - $ref: '#/components/parameters/SailboxId' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/VolumeMount' responses: '200': description: The volume is mounted. content: application/json: schema: type: object example: {} '400': description: >- The request was rejected. See the error message for the offending field. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: memory_limit_gib for size m must be between 8 and 128 type: invalid_request_error param: null code: null '401': description: The API key is missing or invalid. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: Invalid API key type: authentication_error param: null code: invalid_api_key '402': description: >- The organization is out of credits. The error carries a `billing_url` pointing at the page where you add them. Retry once you have. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: >- Your API key has been disabled due to insufficient credits. Visit https://app.sailresearch.com/billing to add credits. type: billing_error param: null code: credits_exhausted billing_url: https://app.sailresearch.com/billing '403': description: The API key is not allowed to perform this operation. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: sailboxes require an organization-scoped API key type: permission_error param: null code: null '404': description: No Sailbox with that id exists in your organization. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: sailbox "sb_9c8f1e2a-3b4d-4f5a-8c7e-1d2f3a4b5c6d" not found type: not_found_error param: null code: null '409': description: The Sailbox is not in a state that allows this operation. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: mount_path overlaps an existing mount type: conflict_error param: null code: null '429': description: >- Too many requests in flight, or the organization is at a limit. A `Retry-After` header means the request never started, so retry it unchanged after that delay. Without one, the request ran and hit the limit `message` names. Some of those clear on their own, such as a shortage of public ports; others need you to free something up first. Send the request again once the cause is gone. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: >- Too many concurrent requests. Please retry after some of your organization's in-flight requests complete. type: rate_limit_error param: null code: rate_limited headers: Retry-After: $ref: '#/components/headers/RetryAfter' '500': description: Server error. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: failed to fetch sailbox type: server_error param: null code: null '503': description: >- Sail is momentarily unavailable. Retry after the delay in the `Retry-After` header when one is present, and with backoff otherwise. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: message: Authentication service unavailable type: server_error param: null code: null headers: Retry-After: $ref: '#/components/headers/RetryAfter' components: parameters: SailboxId: name: sailbox_id in: path required: true schema: type: string description: >- Id of the Sailbox, as returned by create. It is `sb_` followed by a UUID. schemas: VolumeMount: type: object required: - volume_id - mount_path properties: volume_id: type: string minLength: 1 pattern: \S description: Id of a volume you created earlier. mount_path: type: string pattern: ^\s*/. description: >- Absolute path inside the Sailbox where the volume appears. Repeated slashes and `.`/`..` segments are resolved first, and the result cannot be `/`. Two mounts in one request cannot nest inside each other. A new mount requires an absent or empty directory, including in the image. See the [volume guide](https://docs.sailresearch.com/sailbox-sdk#volumes). examples: - /mnt/shared read_only: type: boolean default: false description: >- Mount the volume read-only, fixed for the Sailbox's life. Writes through the mount fail with `EROFS`, even as root. One Sailbox cannot mount the same volume both read-only and writable. See [Volumes](/sailbox-sdk#volumes). ErrorResponse: type: object required: - error properties: error: $ref: '#/components/schemas/ErrorObject' ErrorObject: type: object required: - message - type - param - code properties: message: type: string description: Human-readable description of what went wrong. type: type: string description: >- Error category: `invalid_request_error`, `authentication_error`, `permission_error`, `billing_error`, `not_found_error`, `conflict_error`, `rate_limit_error`, `quota_exceeded_error`, `not_implemented_error`, or `server_error`. param: oneOf: - type: string - type: 'null' description: >- The request field the error refers to, when the error is about one field. code: oneOf: - type: string - type: integer - type: 'null' description: >- Stable short code for the error, when one applies. Errors relayed from the Sailbox runtime carry its status token, for example `already_exists` or `failed_precondition` on a 409, which the HTTP status alone does not distinguish. billing_url: type: string format: uri description: Page where you add credits. Sent with a 402. additionalProperties: true headers: RetryAfter: description: >- How many seconds to wait before retrying. On a 429 it also means the request never started, so the retry can reuse the same `Idempotency-Key`. schema: type: integer minimum: 0 securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key ````