[Yandex Cloud documentation](../../index.md) > [Yandex Managed Service for MySQL®](../index.md) > FAQ > Questions about MySQL

# Questions about MySQL®

* [Which MySQL® versions does Managed Service for MySQL® support?](#supported-version)

* [Is database cluster backup enabled by default?](#backup)

* [Is encryption enabled for MySQL® database cluster connections?](#encryption)

* [What is a read-only replica in MySQL®?](#read-only-instance)

* [What restrictions are placed on MySQL® database clusters?](#instance-limitations)

* [Why is my cluster slow even though the computing resources are not fully utilized?](#throttling)

#### Which MySQL® versions does Managed Service for MySQL® support? {#supported-version}

Managed Service for MySQL® supports MySQL® 5.7 and MySQL® 8.

#### Is database cluster backup enabled by default? {#backup}

Yes, backups are enabled by default. The MySQL® cluster backup policies provide full daily backups and continuous transaction log archiving. This enables you to restore your cluster to any point in time within the backup retention period, except for the last 30 seconds.

#### Is encryption enabled for MySQL® database cluster connections? {#encryption}

Connections between your database cluster and application are always encrypted with SSL. You cannot disable encryption for cluster connections.

#### What is a read-only replica in MySQL®? {#read-only-instance}

A read-only replica is a MySQL® database cluster host available only for reads that synchronizes its data with the master host. This applies only to clusters with more than one host. You can use a read-only replica to reduce the load on the master host experiencing high read traffic to its database.

#### What limitations apply to MySQL® database clusters? {#instance-limitations}

For more on Managed Service for MySQL® limits, see [Quotas and limits](../concepts/limits.md). To learn about the properties of the clusters you can create with Managed Service for MySQL®, see [Host classes](../concepts/instance-types.md).

#### Why is my cluster slow even though the computing resources are not fully utilized? {#throttling}

Your storage may have insufficient maximum [IOPS and bandwidth](../../compute/concepts/storage-read-write.md) to process the current number of requests. In this case, [throttling](../../compute/concepts/storage-read-write.md#throttling) occurs, which degrades the entire cluster performance.

The maximum IOPS and bandwidth values increase by a fixed value when the storage size increases by a certain step. The step and increment values depend on the disk type:

| Disk type                  | Step, GB | Max IOPS increase (read/write) | Max bandwidth increase (read/write), MB/s |
|-----------------------------|---------|------------------------------------|-----------------------------------------------|
| `network-hdd`               | 256     | 300/300                            | 30/30                                         |
| `network-ssd`               | 32      | 1,000/1,000                          | 15/15                                         |
| `network-ssd-nonreplicated`, `network-ssd-io-m3` | 93      | 28,000/5,600                         | 110/82                                        |

To increase the maximum IOPS and bandwidth and reduce the risk of throttling, expand the storage size when [updating your cluster](../operations/update.md#change-disk-size).

For storage using the `network-hdd` disk type, we recommend switching to `network-ssd` or `network-ssd-nonreplicated` via a [cluster restore](../operations/cluster-backups.md#restore) from backup.