# Server tuning

## Using cron to perform background jobs

See Background jobs for a description and the benefits.

## Reducing system load

High system load will slow down Nextcloud and might also lead to other unwanted side effects. To reduce load you should first identify the source of the problem. Tools such as htop, iotop, netdata or glances will help to identify the process or the drive that slows down your system. First you should make sure that you installed/assigned enough RAM. Swap usage should be prevented by all means. If you run your database inside a VM, you should not store it inside a VM image file. Better put it on a dedicated block device to reduce latency due to multiple abstraction layers.

## Log Levels

Verify the `loglevel` in your `config.php`. The default the log level is set to `2` (WARN) in new installations. Sometimes this parameter is inadvertently left at the DEBUG level (`0`) after a troubleshooting event. In some older installations this parameter may also be something other than the default. Use `0` (DEBUG) when you have a problem to diagnose, and then reset your log level to a less-verbose level. DEBUG outputs a lot of information, and can affect your server performance.

## Debug Mode

Verify that `debug` is `false` in your `config.php`. The default is `false` in new installations (or when not specified). While similar to the DEBUG logging level, this option also disables various optimizations (to facilitate easier debugging) and generates additional debug output both at the browser level and server-side. It should not be enabled in production environments outside of isolated troubleshooting situations.

## Caching

Caching improves performance by storing data, code, and other objects in memory. Memory cache configuration for the Nextcloud server must be installed and configured. See Memory caching.

## Compression

Enabling compression in your web server for JavaScript, CSS, and SVG files improves the performance because fewer bytes need to be transferred to the clients.

## Using MariaDB/MySQL instead of SQLite

MySQL or MariaDB are preferred because of the performance limitations of SQLite with highly concurrent applications, like Nextcloud.

See the section Database configuration for how to configure Nextcloud for MySQL or MariaDB. If your installation is already running on SQLite then it is possible to convert to MySQL or MariaDB using the steps provided in Converting database type.

For more details and help tuning your database, check this article at MariaDB.

## Using Redis-based transactional file locking

File locking is enabled by default, using the database locking backend. This places a significant load on your database. See the section Transactional file locking for how to configure Nextcloud to use Redis-based Transactional File Locking.

## TLS / encryption app

TLS (HTTPS) and file encryption/decryption can be offloaded to a processor’s AES-NI extension. This can both speed up these operations while lowering processing overhead. This requires a processor with the AES-NI instruction set.

Here are some examples how to check if your CPU / environment supports the AES-NI extension:

- For each CPU core present: `grep flags /proc/cpuinfo` or as a summary for all cores: `grep -m 1 '^flags' /proc/cpuinfo` If the result contains any `aes`, the extension is present.

- Search eg. on the Intel web if the processor used supports the extension Intel Processor Feature Filter You may set a filter by `"AES New Instructions"` to get a reduced result set.

- For versions of openssl >= 1.0.1, AES-NI does not work via an engine and will not show up in the `openssl engine` command. It is active by default on the supported hardware. You can check the openssl version via `openssl version -a`

- If your processor supports AES-NI but it does not show up eg via grep or coreinfo, it is maybe disabled in the BIOS.

- If your environment runs virtualized, check the virtualization vendor for support.

## Enable HTTP/2 for faster loading

HTTP/2 has huge speed improvements over HTTP with multiple request. Most browsers already support HTTP/2 over TLS (HTTPS). Refer to your web server manual for guides on how to enable HTTP/2.

## Tune PHP-FPM

If you are using a default installation of PHP-FPM you might have noticed excessive load times on the web interface or even sync issues. This is due to the fact that each simultaneous request of an element is handled by a separate PHP-FPM process. So even on a small installation you should allow more processes to run in parallel to handle the requests.

This link can help you calculate the good values for your system.

## Enable PHP OPcache

The OPcache improves the performance of PHP applications by caching precompiled bytecode.

### Revalidation

OPcache revalidation in PHP handles changes made to PHP application code stored on disk. Code changes occur whenever:

- Nextcloud or a Nextcloud app is upgraded

- a configuration change is made (e.g. `config.php` is modified)

Nextcloud, as much as possible, handles cache revalidation internally when required. However this is not foolproof. In a default PHP environment, revalidation is enabled and cached scripts are revalidated to ensure that changes (on disk) take effect every `2` seconds. In many environments, these default values are reasonable (and may never need to be changed).

However, the revalidation frequency can be adjusted and may potentially enhance performance. We make no recommendations here about appropriate values for revalidation (other than the PHP defaults).

Danger

Lengthening the time between revalidation (or disabling it completely) means that manual changes to scripts, including `config.php`, will take longer before they become active (or will never do so, if revalidation is disabled completely). Lengthening also increases the likelihood of transient server and application upgrade problems. It also prevents the proper toggling of maintenance mode.

Warning

If you adjust these parameters, you are more likely to need to restart/reload your web server (mod_php) or fpm after making configuration changes or performing upgrades. If you forget to do so, you will likely experience unusual behavior due to a mismatch between what is on disk and is in memory. These may appear to be bugs, but will go away as soon as you restart/reload mod_php/fpm.

To change the default from `2` and check for changes on disk at most every `60` seconds, use the following setting:

    opcache.revalidate_freq = 60

To disable the revalidation completely:

    opcache.validate_timestamps = 0

Any Server/app upgrades or changes to `config.php` will then require restarting PHP (or otherwise manually clearing the cache or invalidating this particular script).

Warning

To avoid false reports, if your environment isn’t using the PHP default revalidation values, please do not report bugs/odd behavior after upgrading Nextcloud or Nextcloud apps until after you’ve restarted mod_php/fpm (to confirm they are not simply caused by local revalidation configuration).

### Sizing

If any cache size limit is reached by more than 90%, the admin panel will show a related warning and suggested changes.

For more details check out the official PHP documentation. To monitor OPcache usage, clear individual or all cache entries, opcache-gui can be used.

### Comments

Nextcloud strictly requires code comments to be preserved in opcode, which is the default. But in case PHP settings are changed on your system, you may need set the following:

    opcache.save_comments = 1

### JIT

PHP 8.0 and above ship with a JIT compiler that can be enabled on x86 platforms to benefit any CPU intensive apps you might be running. To enable a tracing JIT with all optimizations:

    opcache.jit = 1255
    opcache.jit_buffer_size = 8M

Note

Single Nextcloud instances have shown to use less than 2 MiB of the configured JIT buffer size, so that 8 MiB is sufficient by a large margin. The overall OPcache usage however raises by a larger amount, so that `opcache.memory_consumption` might need to be raised in some cases. The Nextcloud admin panel will then show a related warning. JIT buffer usage can be monitored with opcache-gui as well.

## Previews

It is possible to speed up preview generation using an external microservice: Imaginary.

Warning

Imaginary is currently incompatible with server-side-encryption. See https://github.com/nextcloud/server/issues/34262

We strongly recommend running our custom docker image that is more up to date than the official image. You can find the image at https://ghcr.io/nextcloud-releases/aio-imaginary.

To do so, you will need to deploy the service and make sure that it is not accessible from outside of your servers. Then you can configure Nextcloud to use Imaginary by editing your config.php:

    <?php
    'enabledPreviewProviders' => [
        'OC\Preview\TXT',
        'OC\Preview\MarkDown',
        'OC\Preview\OpenDocument',
        'OC\Preview\Krita',
        'OC\Preview\Imaginary',
    ],
    'preview_imaginary_url' => 'http://<url of imaginary>',

Warning

Make sure to start Imaginary with the -return-size command line parameter. Otherwise, there will be a minor performance impact. The flag requires a recent version of Imaginary (newer than v1.2.4) and is by default added to the aio-imaginary container. Also make sure to add the capability SYS_NICE via –cap-add=sys_nice or cap_add: - SYS_NICE as it is required by imaginary to generate HEIC previews.

Note

For large instance, you should follow Imaginary’s scalability recommendation <https://github.com/h2non/imaginary#scalability>.

### Settings

If you want set the preview format for imaginary. You can change between jpeg and webp, the default is jpeg:

    <?php
      'preview_format' => 'webp',

If you want set a api key for imaginary’:

    <?php
      'preview_imaginary_key' => 'secret',

Default WebP quality setting for preview images is ‘80’. Change this with:

    occ config:app:set preview webp_quality --value="30"

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