Cache Configuration

The cache is the local storage of a Nasuni Edge Appliance. When running a Nasuni Edge Appliance on a virtual platform, you can configure the size of the cache disk and the copy-on-write (COW) disk. On Nasuni hardware appliances, the sizes of the cache disk and the copy-on-write (COW) disk are pre-configured, and there is no need to configure them.

Proper configuration of the cache and related features helps provide the following benefits:

Enables access to data.
Improves the performance experience of users and applications.
Ensures access to data during Internet outages.
Reduces use of network bandwidth.

About the cache

The cache is the local storage of a Nasuni Edge Appliance. All data and metadata that is accessed regularly is kept locally in the cache (“cache resident”). If requested data is not cache resident, the system accesses the requested data from cloud storage, then the data is staged into the cache, and provided for the request.

Note: You don’t have to keep all data locally. A Nasuni Edge Appliance is extremely efficient at keeping only your most-needed data locally and retrieving data from cloud storage as needed.

The size and status of the cache are displayed on the Home page.

Note: Nasuni’s size display might differ from other indications of size, such as Windows Explorer and other utilities. Typically, such utilities display only the size of the data currently present in the local cache, while Nasuni displays the full size, regardless of where the data is.

Note: Nasuni Edge Appliances and the NMC display the size of data in base 10 units (including MB = 1,000,000 bytes, GB = 1,000,000,000 bytes, and TB = 1,000,000,000,000 bytes). In contrast, some platforms display the data size in base 2 units (including MB = 1,048,576 bytes, GB = 1,073,741,824 bytes, and TB = 1,099,511,627,776 bytes). For example, a file that Nasuni displays as 10 MB would be displayed by some platforms as 9.53 MB.

Any data written to a volume is first staged in the local cache. The first Nasuni snapshot preserves each data item from the cache in Nasuni’s cloud storage. Subsequent Nasuni snapshots include only the changes between the original version of the data and the most recent version of the data.

Note: With each Nasuni snapshot, configuration information is included, in case it is necessary to recover the Edge Appliance. The configuration information includes volume name, volume GUID, share type, software version, last pushed version, retention type, and permissions policy. The configuration bundle is encrypted in the same way that all the customer data is encrypted. If you receive an alert that such backup configurations have failed, this might be due to intermittent network issues or possibly due to DNS issues. If you see notifications that the Edge Appliance has successfully completed a snapshot after the backup alert, then you can safely ignore the alert.

The cache continuously tracks “recently changed” data, such as data created or changed since the last Nasuni snapshot. New data that has been saved to the cache but that has not yet been preserved in Nasuni’s cloud storage is classified as “new data in cache not yet protected”.

A chart of New Data in Cache (Not yet protected) appears on the Home page.

The most recently used data remains in the cache, including data, metadata, complete files, or parts of files. Saved data that was written once and rarely used afterwards is eventually released (or “evicted”) from the cache to free up space for new data. If any of this released data is later requested for reads or writes, a Nasuni Edge Appliance retrieves the data from Nasuni’s cloud storage and puts it back into the local cache automatically.

Important: The NMC API can be used to pin metadata in the cache, or to enable Auto Cache for metadata.

Pinning metadata in the cache and enabling Auto Cache for metadata can affect the amount of data in the cache, and the display of data in the cache. Also, bringing all metadata into the cache adds time to the sync process and might affect user performance. With no users on a dedicated appliance (for example, to change permissions or perform searches), the effect on sync times due to syncing the entire metadata tree would not affect any user-related snapshot or sync changes. The NMC API can also be used to verify that these features have been configured for a directory.

Because metadata-only pinning and Auto Cache pinning are currently possible only with the NMC API, directories with such pinning enabled are not displayed in the File Browser of the NMC and the Edge Appliance, nor on the NMC Pinned Folders and NMC Auto Cached Folders pages.

Cache structure

This figure illustrates the structure of the cache:

“Pinned” data is not removed from the cache. If too much cache space is taken up by pinned data, an Alert notification is given.

Reserved space is space set aside in the cache for incoming data. By default, a Nasuni Edge Appliance automatically manages the reserved space. The maximum amount of reserved space is 90 percent of the cache size.

Nasuni snapshots preserve data from the cache in Nasuni’s cloud storage. You can configure the frequency of Nasuni snapshots.

If you receive an alert that such backup configurations have failed, this might be due to intermittent network issues, or possibly due to DNS issues. If you see notifications that the Edge Appliance has successfully completed a snapshot after the backup alert, then you can safely ignore the alert.

Important: The frequency selection represents the average time interval between attempted Nasuni snapshots, not the exact time interval. Randomness is introduced into the time interval in order to reduce possible contention for resources.

For example, if you select a frequency of 1 hour, Nasuni snapshots are not attempted at time intervals of exactly 1 hour. However, the actual time intervals do have an average of 1 hour.

The Quality of Service is the limit on bandwidth for snapshots. The value appears on the Home page.

Considerations for configuring the cache

This section discusses points to consider when configuring the cache.

Warning: Do not use ephemeral disks as the cache for a Nasuni Edge Appliance. While ephemeral disks are low-cost storage options, the data on them is volatile, and utilizing them for Nasuni cache operations exposes you to the loss of unprotected data, if the virtual machine using them is shut down. Ephemeral disks can be automatically selected for cache operations if they are the largest disk attached to the virtual machine when the Nasuni virtual machine is booted.

Since each cloud provider has different policies for attaching ephemeral disks to virtual machines, contact your provider for guidance regarding how to check for this condition. If you do find ephemeral disks attached to an Edge Appliance, contact Nasuni Support to determine if they are being utilized as the cache.

Cache size

The size of the cache should be based on the size of the working set (the amount of data being accessed by users or applications on a regular basis), including metadata.

Note: Cache size has no effect on the cost of Nasuni services. The Nasuni license is based on the storage used, not on cache size.

Cache disk and copy-on-write (COW) disk (aka snapshot disk)

The snapshot (copy-on-write or COW) disk is used during the snapshot process. If any writes to a Nasuni Edge Appliance occur during a snapshot, the previous data from the cache disk is copied to the COW disk, and the new data is written to the cache disk. Hence, the term “copy-on-write”. This allows new writes to occur anytime, even during the snapshot process.

The size of the copy-on-write (COW) disk is determined by how much data can change while a snapshot is running. For example, a heavily used file server, where a lot of data can change while a snapshot is running, might need a larger copy-on-write (COW) disk than a server used mainly for backups, where the snapshot is scheduled for a time when the backup isn't running.

However, if the copy-on-write (COW) disk is too small, then a snapshot might fail, then try again. The snapshot will eventually succeed, but this is very inefficient.

Important: The size of the COW disk should be at least 1/4 of the size of the cache disk. The COW disk need not be larger than 250 GiB, except in special situations where ingestion might exceed the size of the cache disk, such as during initial ingestion or when ingesting extremely large files. In such cases, you can increase the size of the COW disk. For details, see Resizing the Cache and Snapshot Disks.

Tip: Although a Nasuni Edge Appliance issues a warning during startup if the COW disk is too small relative to the cache, a Nasuni Edge Appliance does not issue this warning if the COW disk is larger than 250 GiB.

Note: During the initial boot:

If an ephemeral disk is attached to the appliance, it becomes the copy-on-write (COW) disk.
If there is no ephemeral disk attached to the appliance, the smallest non-OS disk attached to the appliance becomes the COW.
For hypervisors that are not kernel-based virtual machines (KVMs), all other non-ephemeral disks attached to the appliance are automatically combined to be used as the cache disk. To maximize the usage of each disk when they are automatically combined, these non-ephemeral disks should be equal in size.

After the initial boot, you can add another, larger disk to use as the COW disk.

Increasing cache size

For an existing Nasuni Edge Appliance, you can only increase the size of the cache and copy-on-write (COW) disks (snapshot disks). This means that you cannot decrease a value once you have increased it. Therefore, make sure you understand your resizing requirements before you make changes.

Note: If necessary, you can create a new Nasuni Edge Appliance with a smaller cache size, then perform a Disaster Recovery from the existing Nasuni Edge Appliance to the new Nasuni Edge Appliance.

Note: To add cache space by configuring additional cache disks, contact Nasuni Technical Support. Configuring additional cache disks is only possible for Nasuni Edge Appliances whose original version was 7.9 or later.

Cache size and performance

With a larger cache, more data can be cache resident, and access to that data is faster.

On a hardware appliance, more RAM and CPUs also improve performance. Similarly, on a virtual machine, increased physical resources also improve performance.

Performance issues from cache misses

To determine whether performance issues are caused by cache misses, determine which specific files are having problems. Then see if those files are cache resident by clicking File Browser, selecting the volume, navigating to each file, and examining its properties in the Properties pane. If the Cache Resident status is Yes, then the file is cache resident.

Note: A file might be marked as Cache Resident even if only part of the file is present in the cache. To ensure that a given file is cache resident, use Bring into Cache on the File Browser page.

If all other investigation fails to solve performance issues, contact Nasuni Technical Support to analyze the logs to see if many cache misses are happening.

Automatically releasing data from cache

If the amount of cache resident data exceeds a specified percentage of the size of the cache, data is released from the cache until the amount of cache resident data no longer exceeds that specified percentage. Before releasing any data from the cache, a Nasuni Edge Appliance ensures that the data is stored in the cloud. A Nasuni Edge Appliance may perform a snapshot to preserve data in the cloud. Released data is not lost because the data is stored in the cloud, ready to be retrieved.

A Nasuni Edge Appliance releases the least recently used data first, using a sophisticated least recently used (LRU) algorithm.

Loading large amounts of data into a Nasuni Edge Appliance

Nasuni’s best practices for loading large amounts of data into a Nasuni Edge Appliance involve:

Disable remote access temporarily. This makes the snapshots more efficient since they are less concerned with the response time of updates to the remote sites.
Decrease snapshot frequency temporarily. This reduces the demand for resources and allows freer access to the cache.
Enable as much bandwidth (Quality of Service) as can be spared for when snapshots do occur.

Downloading large amounts of data from cloud

To download data from the cloud to the cache faster, do the following:

Make sure that you have sufficient download bandwidth from your ISP.
Adjust the Inbound Limit of the Quality of Service (QoS) rule to the highest rate possible. If the downloading is temporary, you can change or remove the rule when the downloading is complete.
Ensure that the cache space is large enough to receive the data, so the system doesn't have to spend much time making room. You can increase the size of the cache itself or increase the reserved space percentage.

Keeping all data locally (cache resident)

To keep all data cache resident, the size of the non-reserved part of the cache must be larger than the total amount of data you want to keep locally, including metadata. The size of the cache disk must be large enough for the cache. You can then bring all the data into the cache, and pin the data into the cache. If the cache is larger than the total amount of data, all the data remains in the cache, and pinning is unnecessary.

Important: The NMC API can be used to pin metadata in the cache, or to enable Auto Cache for metadata.

Proactively managing the contents of the cache

There are situations where you might need to proactively manage the contents of the cache, because a process might not automatically bring the desired data into the cache. These situations include the following:

After performing a restore.
After performing a Disaster Recovery procedure that includes unpinned data.

You can proactively manage the contents of the cache by performing any of the following actions:

Pinning data in the cache.
Accessing files or folders to ensure they’re brought into the cache.
Bringing data into the cache manually, using Bring into Cache on the File Browser page.

Important: The NMC API can be used to pin metadata in the cache, or to enable Auto Cache for metadata.

Different Nasuni Edge Appliances for different uses

Different uses of a Nasuni Edge Appliance might have different optimum configurations of the cache. For example, the usage pattern for ordinary user access is different from the usage pattern for backups or data mining. To ensure that each use case receives the most suitable configuration, you can set up different Nasuni Edge Appliances for different uses. A Nasuni Edge Appliance is intelligent and does its best to adapt to any use, but you can help guarantee the best behavior for each use case by isolating the use cases on different Nasuni Edge Appliances.

Here are some examples of different uses for Nasuni Edge Appliances:

Primary file server: Pin folders of commonly accessed files, moderate Quality of Service, regular snapshots.
Hot standby for Disaster Recovery: Minimize pinned data, enable Auto Cache, and frequent syncs.
High-performance application: Pin data of commonly accessed files, high Quality of Service, regular snapshots.

Different volumes for different uses

It is also possible to employ different volumes on the same Nasuni Edge Appliance for different purposes. A Nasuni Edge Appliance cache adapts to any use (if Reserved Space Percentage is Automatic), but you can also adjust configurations to accommodate volumes with different uses on the same Nasuni Edge Appliance.

For example, on a single Nasuni Edge Appliance, you might want to use one volume for ordinary user access to data and another for backups. To accommodate these two different uses, you might pin the most used user data in the cache. You might also dedicate a Nasuni Edge Appliance to performing as a file server M-F 8-7, but then do backups at 3 AM.

Cache Specifications

The default cache size on disk is 250 GiB for a VM platform.

The maximum cache size for the Nasuni Edge Appliance depends on the total usable capacity of the VM host. The combined cache and COW disks on each Nasuni Edge Appliance should not consume more than 75 percent of the total capacity of the VM host.

Nasuni has tested cache sizes up to 36 TB. For a larger cache size, consult Nasuni Product Management.

Each platform also has its own maximum disk size. However, multiple cache disks can be combined to form the total cache.

Note: To add cache space:

At first boot: Customers utilizing most hypervisors who want to stripe the Edge Appliance cache across multiple devices can now stripe disks themselves without involving Nasuni Support. The devices must all be the same size and be present when the Edge Appliance boots for the first time. EC2-based, GCP-based, and Nutanix-based Edge Appliances do not support automatic striping at first boot.
After first boot: See Adding Cache Disks.

Quality of cache storage

If you use a Nasuni Edge Appliance hardware appliance, that platform is optimized for the cache.

If you use virtual machines, ensure that the storage platform meets these specifications:

Protection, such as 4+1 RAID-5.
Multiple spindles.
SSD disks.
Battery-backed write cache ability.

Actions affecting the cache

This section describes the actions you can perform that affect the cache.

Removing data from cache

Deleting a volume removes all the volume’s data stored in the cache, as well as data stored in Nasuni’s cloud storage.

Disconnecting from a remote volume removes any data in the cache.

Determining if data is in the cache

By examining a folder or file in the File Browser display, you can determine if a folder or file is currently in the cache (called “cache resident”).

Bringing data into the cache manually

Note: This is optional. Cache management is automatic.

If a file or folder is not in the cache, and you want it in the cache, find it in the File Browser display, then click Bring into Cache.

Note: If accessed data is not in the cache, it is brought into the cache automatically.

Pinning or unpinning folders in the cache

You can enable or disable pinning folders.

On a Nasuni Edge Appliance or the Nasuni Management Console, on the File Browser page, select a folder, then click Edit Cache Settings.

Note: Pinning a folder in the cache does not bring that folder’s data into the cache. Pinning a folder prevents that folder’s data from being removed from the cache.

Important: The NMC API can be used to pin metadata in the cache, or to enable Auto Cache for metadata.

Reserving space in the cache

By default, a Nasuni Edge Appliance automatically manages the percentage of local cache space reserved for new, incoming data, using an advanced algorithm to optimize cache usage. The remainder of the cache retains the data locally that users are most likely to need. However, you can override the percentage reserved for new, incoming data. The percentage you set applies to all volumes on a Nasuni Edge Appliance. The maximum percentage of the cache reserved for new, incoming data is 90 percent of the cache size. The minimum percentage is 5 percent.

By setting the amount of reserved space, you disable the automatic management of this value.

On a Nasuni Edge Appliance, click Configuration, then select Cache Settings. On the Cache Settings page, select Automatic or one of the available percentages from the Reserved Space Percentage drop-down list.

On the Nasuni Management Console, click Filers, then click Cache Settings in the left-hand column. Select Nasuni Edge Appliances, then click Edit Filers.

Snapshots and the cache

Snapshots preserve data from the cache in the cloud, making that data eligible for removal from the cache, if necessary. Thus, scheduling frequent snapshots can help free up room in the cache for incoming writes.

If you receive an alert that such backup configurations have failed, this might be due to intermittent network issues or possibly due to DNS issues. If you see notifications that the Edge Appliance has successfully completed a snapshot after the backup alert, then you can safely ignore the alert.

Chunks

Before sending data to the cloud, Nasuni breaks files into optimally sized pieces for transport between the on-premises cache and cloud storage. This not only disguises the actual sizes of files, but also improves performance. These chunks are then compressed and encrypted.

If the file is smaller than 1 GiB, the default chunk size is 1 MiB. If the file is 1 GiB or larger, and the appliance has less than 16 GiB of RAM, the default chunk size is 2 MiB. If the file is 1 GiB or larger, and the appliance has 16 GiB of RAM or more, the default chunk size is 10 MiB.

For customer-provided clouds, if directed by Nasuni Support, you can adjust the chunk size, or enable or disable Nasuni's compression, using the Cloud I/O area of the Volume Overview page (Nasuni Edge Appliance) or the Volume Cloud I/O page (NMC). If you do manually change the chunk size, the variable chunk size mentioned above no longer operates. You can restore the variable chunk size mentioned above by leaving the Chunk Size field blank and clicking Save.

Scheduling snapshots

You can schedule snapshots on a per-volume basis.

On a Nasuni Edge Appliance, on the Volumes page, select a volume, then click Edit Properties. Click edit next to the Snapshot Schedule status. On the Snapshot Scheduling page, select the days, start time, stop time, and frequency for snapshots.

Important: The frequency selection represents the average time interval between attempted snapshots, not the exact time interval. Randomness is introduced into the time interval to reduce possible contention for resources.

For example, if you select a frequency of 1 hour, snapshots are not attempted at time intervals of exactly 1 hour. However, the actual time intervals do have an average of 1 hour.

Tip: If you have configured a snapshot schedule or a sync schedule for a volume, and if that volume is shared by more than two Edge Appliances, consider enabling the Global File Acceleration (GFA) service on this volume. GFA is a smart and automatic substitute for manually configured snapshot and sync schedules. You use the NMC to configure GFA. GFA must be enabled in your customer license. For details, see the NMC Guide.

On the Nasuni Management Console, on the Volumes page, click Snapshot Schedule, select the volumes to change, then click Edit Volumes.

Tip: On volumes with Global File Lock enabled, we recommend increasing the snapshot frequency and the synchronization frequency of the volume.

If the normal snapshot and synchronization frequency of the volume is decreased, new files take longer to propagate because new files depend on snapshot and synchronization to propagate.

Manually starting snapshots

On a Nasuni Edge Appliance, to take a snapshot sooner than the scheduled time, click “Take snapshot now” on the Volumes page.

On the Nasuni Management Console, on the Volumes page, for the volume that you want to take a snapshot of, click Take Snapshot.

Changing Quality of Service rules

The Quality of Service is the limit on inbound and outbound bandwidth for snapshots. The default inbound Quality of Service is unlimited. The default outbound Quality of Service is 10 megabits per second. The larger the outbound Quality of Service, the faster snapshots complete, and the sooner space can become available in the cache.

On a Nasuni Edge Appliance, to change the Quality of Service rules, click Configuration, then select Quality of Service from the list. On the Quality of Service Settings page, select the days, start time, stop time, and bandwidth limit, from 500 kilobits per second to 25 gigabits per second. You can set up to 12 rules.

On the Nasuni Management Console, on the Filers page, click Quality of Service, select Nasuni Edge Appliances to change, then click Edit Filers.

Changing the size of the cache disk or copy-on-write (COW) disk

On the virtual platform, you can change the size of the disk that a Nasuni Edge Appliance uses for its cache. You can also change the size of the disk that a Nasuni Edge Appliance uses for copy-on-write (COW).

Supported techniques for changing the size of a disk

There are several techniques for achieving cache or snapshot disks of different size:

* To add cache space by configuring additional cache disks, contact Nasuni Technical Support.

** During the initial boot:

If an ephemeral disk is attached to the appliance, it becomes the copy-on-write (COW) disk.
If there is no ephemeral disk attached to the appliance, the smallest non-OS disk attached to the appliance becomes the COW.
For hypervisors that are not kernel-based virtual machines (KVMs), all other non-ephemeral disks attached to the appliance are automatically combined to be used as the cache disk. In order to maximize the usage of each disk when they are automatically combined, these non-ephemeral disks should be equal in size.

After the initial boot, you can add another, larger disk to use as the COW disk.

*** You cannot delete the built-in COW disk, but you can add a new COW disk of a different size. The largest unused disk becomes the new COW disk. Note that this requires assistance from Nasuni Support for configuration.

‡ For Amazon EC2, you can decrease the cache size using the VM user interface, but you must perform a recovery procedure of the Edge Appliance afterwards. If you are increasing the size of the cache using the VM user interface, you do not need to perform a recovery procedure of the Edge Appliance afterwards.

Important: The size of the COW disk should be at least 1/4 of the size of the cache disk. The COW disk need not be larger than 250 GiB, except in special situations where ingestion might exceed the size of the cache disk, such as during initial ingestion or when ingesting extremely large files. In such cases, you can increase the size of the COW disk. For details, see Resizing the Cache and Snapshot Disks.

Striped disks

If you are using a striped cache disk configuration, you must increase each cache disk by an equal amount. For example, if you currently have a 1 TB cache made up of four 250 GB disks, and you want to have a 2 TB cache, you must increase each cache disk individually by 250 GB.

Using the VM user interface to increase the size of the cache disk or copy-on-write (COW) disk

On the VMware ESX/ESXi and Microsoft Hyper-V virtual platforms, you can increase the size of the cache disk and the COW disk.

Note: There must be sufficient disk space in the datastore to increase the disk size.

Note: You must shut down the virtual machine to change the disk size.

Note: Nasuni supports VMware ESXi 7.0 and above.

Caution: Perform a manual snapshot on a Nasuni Edge Appliance before changing the size of the disk.

Tip: Nasuni recommends using Thick provisioning for all virtual disks for performance reasons. On the VMware virtual platform, Nasuni recommends Thick Provision Eager Zeroed. Thin provisioning is not supported because acceptable performance is unlikely.

Warning: Do not attempt to restore from a virtual machine snapshot or backup.

Warning: Never delete the cache disk.

vSphere Client platform

Note: If you have taken a VMware snapshot, you cannot change the size of the disk. You must delete the VMware snapshot first.

Warning: Do not attempt to restore from a virtual machine snapshot or backup.

To change the size of the disk on the vSphere Client platform, follow these steps:

Launch the VMware vSphere Client. The VMware vSphere Client login window appears.
Log in to the vSphere Client with a valid IP address and your user name and password. The vSphere Client opens.
In the pane on the left, expand the host to display the list of virtual machines.
Click the name of your Nasuni Edge Appliance. This is the name you entered when you installed a Nasuni Edge Appliance. Information about your Nasuni Edge Appliance appears in the right pane.
If the virtual machine is running, then shut down the virtual machine using these steps.
a. On the Console tab, click in the command line area.
b. Press Enter.
c. Enter the login name and password for the service console. The default login name is service and the default password is service.
d. Enter shutdown.
e. Confirm the shutdown by entering yes. The virtual machine shuts down.
On the Getting Started tab, click Edit virtual machine settings.
Alternatively, on the Summary tab, click Edit Settings.
Alternatively, right-click the name of your Nasuni Edge Appliance in the list of virtual machines, then select Edit Settings from the drop-down list. The Virtual Machine Properties dialog box appears.
On the Hardware tab, select the desired disk in the Hardware list on the left side.
Note: During the initial boot:
- If an ephemeral disk is attached to the appliance, it becomes the copy-on-write (COW) disk.
- If there is no ephemeral disk attached to the appliance, the smallest non-OS disk attached to the appliance becomes the COW.
- For hypervisors that are not kernel-based virtual machines (KVMs), all other non-ephemeral disks attached to the appliance are automatically combined to be used as the cache disk. To maximize the usage of each disk when they are automatically combined, these non-ephemeral disks should be equal in size.
After the initial boot, you can add another, larger disk to use as the COW disk. Information about the selected hard disk appears on the right side.
Enter or select the new Provisioned Size. The Provisioned Size must be less than or equal to the displayed Maximum Size of that hard disk. The new Provisioned Size must be greater than the previous Provisioned Size.
For details on the size of the cache disk, see “Cache Specifications” on page 12.
Tip: If necessary, it is possible to reduce the size of the copy-on-write disk. To do this, shut down the Nasuni Edge Appliance (see the Nasuni Edge Appliance Administration Guide for instructions), delete the existing copy-on-write disk, create a new copy-on-write disk with the desired size, and then restart the Nasuni Edge Appliance.
Click OK. The size of the selected hard disk changes to the specified size.
If you have configured more than one cache disk, repeat step 7, step 8, and step 9 for each cache disk.
On the Getting Started tab, click Power on the virtual machine. Alternatively, on the Summary tab, click Power On.
Alternatively, right-click the name of your Nasuni Edge Appliance in the list of virtual machines, then select Power from the drop-down list, then select Power On from the drop-down list.
The virtual machine powers on. After a significant cache resize, the operations after powering on can take some time, with some performance impact during that period. The progress of the cache resize is visible on the Nasuni Edge Appliance user interface.

Hyper-V Manager platform

To change the size of the disk on the Hyper-V Manager platform, follow these steps:

Launch Hyper-V Manager.
In the Virtual Machines list, click the name of your Nasuni Edge Appliance. This is the name you entered when you installed the Nasuni Edge Appliance. Information about your Nasuni Edge Appliance appears.
If the virtual machine is running, then follow these steps:
a. In the Virtual Machines list, right-click the name of your Nasuni Edge Appliance, then select Shut Down from the drop-down list. Alternatively, in the Virtual Machines list, select the name of your Nasuni Edge Appliance, then click Shut Down in the list of actions on the right side. The Shut Down Machine dialog box appears.
b. Click Shut Down. The virtual machine shuts down.
In the Virtual Machines list, right-click the name of your Nasuni Edge Appliance, then select Settings from the drop-down list. Alternatively, in the Virtual Machines list, select the name of your Nasuni Edge Appliance, then click Settings in the list of actions on the right side. The Settings dialog box appears.
In the Hardware list on the left side, select the desired hard drive. The default label for the cache hard drive is “Hard Drive Cache.vhd”. The cache hard drive is the largest hard drive. The default label for the copy-on-write (COW) hard drive is “Hard Drive Cow.vhd”. Information about the selected hard drive appears on the right side.
Click Edit. The Edit Virtual Hard Disk Wizard dialog box appears.
Select Expand, then click Next.
Enter the New size of the disk. The “New size” must be less than or equal to the displayed Maximum size of that hard disk. The “New size” must be greater than the previous size. Then click Next.
When you resize the cache, Nasuni recommends that the cache disk be no more than four times the size of the copy-on-write or COW disk.
For details on the size of the cache disk, see “Cache Specifications” on page 11.
Click Finish. The size of the disk changes to the specified size.
If you have configured more than one cache disk, repeat step 5, step 6, step 7, step 8, and step 9 for each cache disk.
Click OK. The Settings dialog box closes.
In the Virtual Machines list, right-click the name of your Nasuni Edge Appliance, then select Start from the drop-down list. Alternatively, in the Virtual Machines list, select the name of your Nasuni Edge Appliance, then click Start in the list of actions on the right side.
The virtual machine restarts. After a significant cache resize, the operations after powering on can take some time, with some performance impact during that period. The progress of the cache resize is visible on the Nasuni Edge Appliance user interface.

Using the Disaster Recovery procedure to change the size of the cache disk or copy-on- write (COW) disk

On all virtual platforms, you can change the size of the cache disk and the COW disk using the Disaster Recovery procedure.

Tip: Although a Nasuni Edge Appliance issues a warning during startup if the COW disk is too small relative to the cache, a Nasuni Edge Appliance does not issue this warning if the COW disk is larger than 250 GiB.

First, create a new Nasuni Edge Appliance on the platform. The new Nasuni Edge Appliance should have the correct size of cache and COW disks.

Note: To add cache space by configuring additional cache disks, contact Nasuni Technical Support.

Next, perform a manual Nasuni snapshot on the existing Nasuni Edge Appliance, then shut down the existing Nasuni Edge Appliance.

Finally, perform a Disaster Recovery procedure to the new Nasuni Edge Appliance.

Using a new COW disk to change the size of the COW disk

On all virtual platforms, you can change the size of the COW disk by creating a new COW disk.

Tip: Although a Nasuni Edge Appliance issues a warning during startup if the COW disk is too small relative to the cache, a Nasuni Edge Appliance does not issue this warning if the COW disk is larger than 250 GiB.

First, perform a manual Nasuni snapshot on the existing Nasuni Edge Appliance, then shut down the existing Nasuni Edge Appliance.

Next, on all platforms except the Microsoft Azure platform, delete the existing COW disk. Then, create a new COW disk with the correct size.

Finally, restart the Nasuni Edge Appliance.

On the Microsoft Azure platform, the largest unused disk becomes the new COW disk. Note that this requires assistance from Nasuni Support for configuration.