DOCS-6635, DOCS-7444, DOCS-8610: prodnotes hardware considerations revisions

Author: schmalliso

source/administration/production-checklist-operations.txt

@@ -168,12 +168,23 @@ Linux
      </tutorial/transparent-huge-pages>` for more information.
 
    - :ref:`Adjust the readahead settings <readahead>` on the devices
-     storing your database files to suit your use case. If your working
+     storing your database files to suit your use case.
+     For the MMAPv1 storage engine, if your working
      set is bigger that the available RAM, and the document access
      pattern is random, consider lowering the readahead to 32 or 16.
      Evaluate different settings to find an optimal value that maximizes
      the resident memory and lowers the number of page faults.
 
+     For the WiredTiger storage engine, set readahead to 0 or 16.
+
+   - Disable the ``tuned`` tool if you are running RHEL 7 / CentOS 7 in a
+     virtual environment.
+
+     When RHEL 7 / CentOS 7 run in a virtual environment, the ``tuned`` tool
+     automatically invokes a performance profile derived from
+     performance throughput, which automatically sets the readahead
+     settings to 4MB. This can negatively impact performance.
+
    - Use the ``noop`` or ``deadline`` disk schedulers for SSD drives.
 
    - Use the ``noop`` disk scheduler for virtualized drives in guest VMs.

source/administration/production-notes.txt

@@ -1,4 +1,4 @@
-================
+m================
 Production Notes
 ================
 
@@ -281,6 +281,15 @@ reads/writes in the (``ar|aw``) column.
 
 .. include:: /includes/extracts/wt-configure-cache.rst
 
+Compression and Encryption
+``````````````````````````
+
+When using encryption, CPUs equipped with AES-NI instruction-set
+extensions show significant performance advantages.
+If you are using MongoDB Enterprise with the
+:ref:`encrypted-storage-engine`, choose a CPU that supports AES-NI for
+better performance.
+
 .. seealso:: :ref:`prod-notes-concurrency`
 
 Use Solid State Disks (SSDs)
@@ -289,7 +298,6 @@ Use Solid State Disks (SSDs)
 MongoDB has good results and a good price-performance ratio with
 SATA SSD (Solid State Disk).
 
-
 Use SSD if available and economical. Spinning disks can be
 performant, but SSDs' capacity for random I/O operations works well
 with the update model of MMAPv1.
@@ -346,16 +354,20 @@ When running MongoDB on Linux, you should disable *zone reclaim* in the
 
    sudo sysctl -w vm.zone_reclaim_mode=0
 
-Then, you should use the ``numactl`` command to start the MongoDB programs
-(:program:`mongod`, including the :doc:`config servers
-</core/sharded-cluster-config-servers>`; :program:`mongos`; and clients) in
-the following manner:
+Then, you should use ``numactl`` to start your
+:program:`mongod` instances, including the :doc:`config servers
+</core/sharded-cluster-config-servers>`, :program:`mongos` instances, and any clients.
+If you do not have the ``numactl`` command, refer to the documentation for
+your operating system to install the ``numactl`` package.
+
+The following operation demonstrates how to start a MongoDB instance
+using ``numactl``:
 
 .. code-block:: sh
 
    numactl --interleave=all <path> <options>
 
-where ``<path>`` is the path to the program you are starting, and ``<options>``
+The ``<path>`` is the path to the program you are starting and the ``<options>``
 are any optional arguments to pass to the program.
 
 To fully disable NUMA behavior, you must perform both operations. For more
@@ -419,7 +431,9 @@ Separate Components onto Different Storage Devices
 
 For improved performance, consider separating your database's data,
 journal, and logs onto different storage devices, based on your application's
-access and write pattern.
+access and write pattern. Mount the components as separate filesystems
+and use symbolic links to map each component's path to the device
+storing it.
 
 For the WiredTiger storage engine, you can also store the indexes on a
 different storage device. See
@@ -433,14 +447,26 @@ different storage device. See
 
 .. _virtualized-disks-scheduling:
 
-Scheduling for Virtual Devices
-``````````````````````````````
+Scheduling
+``````````
+
+Scheduling for Virtual or Cloud Hosted Devices
+++++++++++++++++++++++++++++++++++++++++++++++
 
-Local block devices attached to virtual machine instances via the
-hypervisor should use a *noop* scheduler for best performance. The
+For local block devices attached to a virtual machine instance via
+the hypervisor or hosted by a cloud hosting provider, the guest operating system
+should use a *noop* scheduler for best performance. The
 *noop* scheduler allows the operating system to defer I/O scheduling to
 the underlying hypervisor.
 
+Scheduling for Physical Servers
++++++++++++++++++++++++++++++++
+
+For physical servers, the operating system should use a *deadline*
+scheduler. The *deadline* scheduler caps maximum latency per request
+and maintains a good disk throughput that is best for disk-intensive
+database applications.
+
 Architecture
 ------------
 
@@ -561,10 +587,18 @@ consider the following recommendations:
 
   .. include:: /includes/fact-selinux-server-side-js.rst
 
-For the **MMAPv1** storage engine:
-
 .. _readahead:
 
+For the **WiredTiger** storage engine:
+
+- Set the readahead setting to 0 or 16. Setting a higher readahead
+  benefits sequential I/O operations. However, since MongoDB disk
+  access patterns are generally random, setting a higher readahead
+  provides limited benefit. As such, for most workloads, a readahead of
+  0 or 16 provides optimal MongoDB performance.
+
+For the **MMAPv1** storage engine:
+
 - Ensure that readahead settings for the block devices that store the
   database files are appropriate. For random access use patterns, set
   low readahead values. A readahead of 32 (16 kB) often works well.