Data Protection Tool

The best technique to properly sizing a Datto SIRIS

Picture of Dale Shulmistra

Dale Shulmistra

Data Protection Specialist @ Invenio IT



Properly sizing a Datto SIRIS backup solution is very important.

When done correctly, it will ensure that your data is backed up today, and also in the future. Determining that a Datto SIRIS is properly sized based on the ratio of the Datto Device’s Primary Storage size to the sum of the sizes of each protected volume.

Please note that this article does not take into consideration usage of the NAS share feature available in the Web Consoles.  In the event that the SIRIS NAS share is being used simply subtract the NAS share’s used space from the total size of the device.

Datto’s 2.5x to 4x multiplier

As a general rule, based on each SIRIS’s default retention policy, it is recommended to choose a model which has a Primary Storage size that is 2.5x that of the total amount of the size of the protected volumes. We find a 3x multiplier is better if there are large transactional servers like SQL, and 4x if you decide to decrypt the agents.

The 2.5x – 4x multiplier ensures that the device will have the storage space needed to:

• Store the first backup which becomes the initial base image and later continuously roll this base image to the front of the chain with each backup.

When the stored backups in the primary storage of a SIRIS device reaches 100% of it’s capacity the backups will start to fail.

• Provide storage space for backups to be stored for each of the 168 hours in the previous week, one backup from each day for 28 days, & one backup for each week for 90 days (~12 weeks).

Devices that fill up before the end of the retention policy for the device is reached result in failed backups.

•  Provides a slight safety buffer for cases in which mild unexpected data growth could potentially occur over time.

When a SIRIS device’s Primary Storage Space reaches maximum capacity the optional resolution paths may be more difficult.

Datto Datto SIRIS’s Default Retention Policy

Viewing the retention policy for a protected machine on the Siris Web console can be done so by selecting the link entitled “Basic Options” on the Web Console.

By default these values will be:

    • 168 Hourly Backups per week.
    • Convert intra-daily backups to dailies after 7 days.
    • Convert dailies to weekly backups after 4 weeks.
    • Delete backups locally after 90 days.

properly sizing a datto siris 1

Example: Backup Retention displayed under Basic Options section

Properly sizing a Datto SIRIS

The first page that appears when launching the Web Console displays a section called “Storage Status” on the left sidebar.

From the “Storage Status” section of the left sidebar two important fields are displayed:

    • Primary Storage: This displays the used, available, & total size of the Primary Storage (the storage array) of the device.
    • Total Protected: This value takes the size of all protected volumes for every protected machine and displays the sum.

Please Note: The Total Protected size should not exceed 50% of the Primary Storage’s Total Capacity.

In cases where the Total Protected size is greater than 50% of the Primary Storage’s Total Capacity the device will likely reach 100% capacity.  When this occurs what will very likely result is failed backups until existing recovery points are deleted to make more space available.

properly sizing a datto siris 1

Handling of “Edge” Cases & Unique Retention Policies

When the Total Protected size is slightly larger than 50% of the Primary Storage’s Total Capacity, as seen in the “Slightly undersized SIRIS” example above, setting a slightly more conservative retention policy may help to avoid having the Datto SIRIS reach full capacity.

If a retention policy is requested that is longer and/or more frequent than the default retention policy it is suggested to work with your Invenio IT Sales associate to help properly size the device to support the storage of the number of recovery points needed.

Resolutions available for when too much data is being protected by a SIRIS Device

Reducing the amount of used disk space on the Protected Machine and/or it’s volumes can help to avoid consequences of an undersized SIRIS.

Many Datto Partners have had great success determining which directories contain the most amount of data by using the Open Source Tool WinDirStat.

Keep in mind that once data has been removed from the Protected Machines themselves that previously taken backups still contain this data. Due to this in some situations it may be required to remove previous recovery points from the web console to relieve space from the Primary Storage of the SIRIS.

Disable backups of a specific volume on the local SIRIS Web Console.

    • The “Volume Level Backup Control”  is available by selecting “Advanced Options” for a protected machine.
    • Tip: If a “System Reserved” volume is listed for a machine running Windows Server 2008r2 or Windows 7, do not uncheck this volume as it will hamper virtualization and is typically only 100MB in size.

properly sizing a datto siris 1

Example: Volume Level Backup Control section of Advanced Options

Modifying default retention policies in the local Siris Web Console

    • Choosing a conservative retention policy of a protected machine can be done for just one machine or for all machines protected by the SIRIS.
    • Simply click “Basic Options” for any protected machine on the local SIRIS’s Web Console to find the “Backup Retention” options.
    • Note: The retention policy will not actually be applied until the next backup successfully completes.  In events where the Siris is 100% full removal of one or more recovery points to provide space for the next backup will be required to apply retention.

Example: Backup Retention Displayed in Basic Options

Modify the Backup Schedule in the local SIRIS Web Console

    • Configuring a backup schedule of a protected machine can be done for just one machine or for all machines protected by the Datto SIRIS.
    • Simply click “Basic Options” for any protected machine on the local Web Console to find the “Backup Schedule” options.
    • Tip: The hours of the day & days of the week themselves can be clicked to remove all check boxes in their set.

properly sizing a datto siris 5

Example: Set Backup Schedule Displayed in Basic Options

For further assistance in properly sizing a Datto SIRIS, check out this video or contact Invenio IT Support at (646) 395 – 1170.

Get More out of your Datto SIRIS with these expert best practices.
Invenio it logo

Join 23,000+ readers in the Data Protection Forum

Related Articles