Choosing S3 for Disaster Recovery

In addition to on-premises Swarm storage, an organization may want to take advantage of public cloud services for off-premises disaster recovery (DR) storage. With the S3 protocol support, Swarm provides choices of many public cloud providers including AWS S3, AWS S3 Glacier, and Wasabi. 

The security of knowing backups are continuous, have minimal latency, and require little intervention and monitoring by implementing an S3 backup feed from Swarm. Using Swarm's feed mechanism for backup leverages numerous existing strengths: the long-term iteration over objects in the cluster, proven method for tracking work as it is performed, and support for TLS network encryption and forward proxies. Using the parallelism of the entire Swarm cluster makes best use of network bandwidth, while sending the backups through an optional forward proxy allows implementing bandwidth throttling if needed.

Back up — S3 Backup is an integral part of the operating Swarm cluster. In the Swarm UI, create a new feed of type S3 Backup, provide credentials and information about the network path to the service. After the feed is started, progress can be monitored and warning of blockages and particular object failures can be sent, as with any other feed. The S3 Backup feed honors the versioning settings in a cluster, as enabled, disabled, or suspended throughout the domains and buckets. While multiple S3 Backup feeds can be created, each one requires a dedicated target bucket.

Clean up — No action is needed to keep the backup current and trimmed. When disabling Swarm versioning on buckets or domains, delete buckets or domains, or have object lifepoints expire, the Swarm feeds mechanism processes the expired content as deleted, allowing the S3 Backup feed to clear them from the S3 bucket. Throughout content additions and deletions, the total number objects in the S3 bucket always approximates twice the number of logical objects backing up from the source cluster (because AWS functionality requires there to be one for the object's content and another for metadata).

Restore — The Restore tool runs outside of Swarm, using a command-line interface for executing the data and restoration tasks. Restore what is needed: either the entire cluster, or portions. Swarm supports bulk restores at the granularity of cluster, domain, or bucket, as well as more surgical restores of a few objects. Multiple copies can be run to achieve a faster, parallel recovery. See the S3 Backup Restore Tool.

Standard or Cold Storage?

Swarm 12 supports the AWS S3 storage classes for standard buckets and those using S3 Glacier and S3 Glacier Deep Archive. For this discussion, cold storage refers to S3 Glacier and S3 Glacier Deep Archive, and standard storage refers to the traditional S3 storage classes.

Refer to the documentation for the public cloud provider, and consider these points when choosing among the AWS S3 storage classes:

• Cold storage offers the lowest monthly prices per byte stored compared to the standard storage classes.

• Standard storage classes have low-latency retrieval times, which can allow a Swarm Restore to complete in a single run.

• Cold storage has longer retrieval latency, as much as 12-48 hours for S3 Glacier Deep Archive, to pull content from archival storage. Depending upon how a restore is performed, the Swarm Restore tool may need to be run multiple times over several hours in order to complete a restoration.

• Cold storage incurs additional charges for egress and API requests to access the backup, so it is best suited to low-touch use cases.

• S3 Glacier Deep Archive rounds up small objects, so the overall footprint being charged may be larger because of Swarm's use of metadata objects.

Public storage pricing is competitive, and services such as Wasabi Hot Cloud Storage may compare favorably with AWS cold storage, especially when considering egress and API charges.

Setting up the S3 Bucket

To implement an S3 backup feed, first complete a one-time set up of the S3 side: set up an account with an S3 cloud service provider and then create an S3 bucket dedicated to backing up this cluster.

While these instruction steps are for AWS S3 (see also S3 Backup Feeds to Wasabi), S3-based public cloud providers have a similar setup process:

1. Service — Sign up for Amazon S3 if needed.

   1. Navigate to aws.amazon.com/s3 and choose Get started with Amazon S3.

   2. Follow the on-screen instructions.

   3. AWS notifies by email when the account is active and ready to use.

   4. Note: S3 is accessed for the new bucket but the separate IAM service for the new user:
      

      

2. Bucket — Create a bucket dedicated to backing up the Swarm cluster.

   1. Sign in and open the S3 console: console.aws.amazon.com/s3

   2. Choose Create bucket. (See S3 documentation: Creating a Bucket.) 

   3. On tab 1 - Name and region, make the initial entries:

      1. For Bucket name, enter a DNS-compliant name for the new bucket. This cannot be changed later, so choose well:

         1. The name must be unique across all existing bucket names in Amazon S3.

         2. The name must be a valid DNS name, containing lowercase letters and numbers (and internal periods, hyphens, underscores), between 3 and 64 characters. (See S3 documentation: Rules for Bucket Naming.)
            Tip: For easier identification, incorporate the name of the Swarm cluster that this bucket is dedicated to backing up.

      2. For Region, choose the one that is appropriate for business needs. (See S3 documentation: Regions and Endpoints.)

   4. On tab 2 - Configure options, take the defaults. (See S3 documentation: Creating a Bucket, step 4.)
      Best practice: Do not enable versioning or any other optional features, unless it is required for the organization.

   5. On tab 3 - Set permissions, take the default to select Block all public access; now the bucket owner account has full access.
      Best practice: Do not use the bucket owner account to provide Swarm's access to the bucket; instead, create a new, separate IAM user that holds the credentials to share with Swarm. 

   6. Choose Create, and record the fully qualified bucket name (such as "arn:aws:s3:::example.cluster1.backup") for use later, in policies.

   7. Record these values for configuring the S3 Backup feed in Swarm:

      • Bucket Name

      • Region

3. User — Create a programmatic (non-human) user dedicated to Swarm access.

   1. On the Amazon S3 console, select the service IAM (Identity and Access Management), click Users.
      
      

   2. Add a dedicated user, such as caringo_backup, to provide Programmatic access for Swarm.
      
      

   3. The IAM console generates an access key (an access key ID + secret access key), which must be recorded immediately.
      (See S3 documentation: Managing Access Keys for IAM Users and Understanding and Getting Your Security Credentials.)

      • This is the sole opportunity to view or download the secret access key, so save it in a secure place.

   4. Record the fully qualified user (such as "arn:aws:iam::123456789012:user/caringo_backup") for use later, in policies.

   5. Record these values for configuring the S3 Backup feed in Swarm:

      • Access Key ID

      • Secret Access Key

4. Policies — Create policies on both the user and the bucket so the programmatic user has exclusive rights to the S3 bucket. Use the policy generators provided or enter edited versions of the examples below.

   1. Create an IAM policy for this user, allowing it all S3 actions on the backup bucket, which need to be specified as a fully qualified Resource (recorded above), starting with arn:aws:s3:::
      

      IAM policy

      {
          "Version": "2012-10-17",
          "Statement": [
              {
                  "Effect": "Allow",
                  "Action": "s3:*",
                  "Resource": "arn:aws:s3:::example.cluster1.backup"
              }
          ]
      }

      
      

   2. Create a matching bucket policy to grant access to the dedicated backup user, which need to be specified as a fully qualified Principal, which is the User ARN (recorded above) starting with arn:aws:iam:: (See S3 Using Bucket Policies.) 
      Using the Policy Generator, allow all S3 actions for the bucket, using the full ARN name:
      

      Bucket policy

      {
        "Id": "Policy1560809845679",
        "Version": "2012-10-17",
        "Statement": [
          {
            "Sid": "Stmt1560809828003",
            "Action": "s3:*",
            "Effect": "Allow",
            "Resource": "arn:aws:s3:::example.cluster1.backup",
            "Principal": {
              "AWS": [
                "arn:aws:iam::123456789012:user/caringo_backup"
              ]
            }
          }
        ]
      }

      
      

5. Best practice for security: After implementing the S3 Backup feed in Swarm, write a script to automate rotation of the S3 secret access key on a regular basis, including updating in the S3 Backup feed definition in Swarm (using the management API call, given in Rotating the S3 Access Key, below).
   

Configuring the S3 Backup Feed

The S3 Backup Feed option is available in Swarm 11 and higher, and it may be used immediately after upgrading Swarm Storage. (v11.0)

In addition to Swarm's other feed types, Search and Replication, a dedicated S3 Backup feed can be created. It resembles a Replication feed, but it requires an S3 bucket as the destination and has defaults appropriate for use with a cloud service.

1. Navigate to the Feeds page.
   

2. Select + Add at the top right.
   

   

3. Choose the S3 Backup feed type:
   

   

An S3 Backup feed has these parameters:

ID (existing feeds)	Read-only; system-assigned identifier
Status (existing feeds)	Read-only; the current feed processing state. The state can be: Active. Default state when operating normally. Recovering. Temporarily paused due to volume recovery. Paused. Paused by user request. Blocked. Processing blocked due to a transient condition.  Configuration error. Feed is unable to operate due to incorrect configuration Overlapping feeds. More than the limit of 8 feeds are defined for the same set of objects. Closed. Feed is inactive and no longer operational.
Name	The name attached to this backup feed.
Scope	The scope filter selected for the backup feed. Backup includes objects within the scope indicated here. If the scope includes a context where Swarm object versioning is (or was) generating historical versions, those versions are backed up as well. Entire source cluster (global) — To replicate all objects in the source cluster, leave the default selection of Entire source cluster (global) Only objects in select domain(s) — To replicate the objects in one or more domains, select the 'Only objects in select domain(s) option. In the text box that appears, enter one or more domains: To replicate the objects within a specific domain, enter that domain. To replicate the objects within multiple domains, enter those domains separated by commas and/or use pattern matching. To exclude domains from replication, enter them. The field value allows pattern matching with the Python regular expression (RE) syntax so multiple domain names can be matched. The exception to the RE matching is that the "{m,n}" repetitions qualifier may not be used. An example domain list value using RE is: .*\.example\.com  This matches both of these domains: accounting.example.com, engineering.example.com. Include objects without a domain — To replicate any unnamed objects that are not tenanted in any domain, enable the option.
Target S3 Provider	The configuration for the S3 bucket. Caution Although it is possible to specify another Swarm cluster (via Content Gateway S3) for the S3 backup, it is risky if there is any chance of it replicating back to the source cluster: both clusters can fill to capacity with backups of backups. Best practice is to use a regular Replication feed, which has the mechanisms needed for mirroring clusters safely.
Host	From the S3 configuration, the host name of the S3 service. An IP address cannot be used here because the host name itself becomes the Host header in the feed operation, which is required for communication to S3 services. Important: Add the bucket name as the prefix to the host name (mybackup.s3.aws.com). This prefix must match the bucket name exactly, including case. This supports the new AWS bucket-in-host request style. If the bucket is not defined here, Swarm uses the legacy bucket-in-path (s3.aws.com/mybackup) request style. (v12.0)  Amazon AWS: Existing feeds are not required to change to this format immediately, but new ones should, as bucket-in-path is unsupported in the future.  Other S3 provider: Verify the provider supports the bucket-in-host request style, where the bucket is part of the FQDN; if not, use bucket-in-path.
Port	The port to use for the S3 service, which defaults to 443 (for HTTPS) or else 80 (HTTP), if Require trusted SSL is disabled, below. If the port is customized, the value no longer updates based on changes to the SSL setting.
Region	From the S3 configuration, the destination S3 bucket’s region.  Note: Changing this value triggers a restart of the feed.
Bucket	From the S3 configuration, the destination S3 bucket name. This bucket must be dedicated to one source cluster. Complete this field regardless of whether the Host includes the bucket name as a prefix. Note: Changing this value triggers a restart of the feed.
Access key ID and secret key	From the S3 configuration, the S3 access key ID and S3 secret access key to use. (See S3 documentation: Understanding and Getting Your Security Credentials.) Swarm protects the secret key as a secure field, and hides it. Updating the key does not trigger a restart of the feed, so keys may be updated as frequently as the security policies require.
SSL Server	For production usage, select Require trusted SSL. Recommended: To keep bandwidth usage by the S3 Backup feed in check, select the option to use a Local Cluster Forward Proxy and configure one for that purpose. The Forward Proxy Host (hostname or IP address) and Port are required.
Threads	The default backup speed (6 simultaneous threads) is optimal for maintaining an existing S3 backup.  For a faster initial backup, increase the threads temporarily, but monitor bandwidth and cluster performance, as boosting the speed stresses internet bandwidth.

Rotating the S3 Access Key

It is a DevOps best-practice to routinely change cloud access credentials and to automate this S3 access key rotation for the S3 Backup feed.

1. Through the public cloud provider, create a new S3 access key and grant the correct permissions for the target S3 bucket.

2. Using Swarm's management API, update the access credentials for the existing S3 backup feed.

3. Expire/remove the old S3 access key upon confirming successful feed operations with the new credentials.

The following command template demonstrates how to use the Swarm management API to update the access credentials for an existing S3 backup feed:

curl -X PATCH --header 'Content-Type: application/json' -u <admin>:<password> -d '[       \
{"op": "replace", "path":"destination/accessKeyId", "value":"<newAccessKeyID>"},          \
{"op": "replace", "path":"destination/secretAccessKey", "value":"<newSecretAccessKey>"}]' \
'http://<nodeIP>/api/storage/s3backupfeeds/<s3feedid>'

• <admin> — The Swarm administrative user name, which is usually admin.

• <password> — The Swarm administrative password, required for all management API calls that perform actions.

• <newAccessKeyID> — The new access key ID for the target S3 bucket.

• <newSecretAccessKey> — The new secret access key for the target S3 bucket.

• <nodeIP> — The IP address of any Swarm node in the cluster.

• <s3feedid> — The small integer feed ID that is associated with the S3 Backup feed. It appears as the feed's ID field in the Swarm UI.

Using Feed Actions

Clicking on an existing feed in the Feeds list opens the Feed Settings page, with the existing settings populated. The Actions (gear) icon menu at the top right supports multiple feed actions, appropriate to the type of feed:

Troubleshooting Feeds

• Feed Diagnostics: Double-click a blocked feed to open the settings page, click the gear icon, and select View feed table, which displays the SNMP Repository Dump for the selected node to troubleshoot. (v2.0)
  

  

  Review the feedPluginState status to identify the blockage. 
  Example: feedPluginState blocked: Destination cluster onyx1 reports invalid request: Castor-System-Cluster value must refer to a remote cluster on RETRIEVE request

• Idle Feeds: A feed can appear to be idle with items still queued for processing. Plan for the fact that feed status reporting is a best-effort snapshot, not a low-latency or guaranteed transaction mechanism.

• Feed Prioritization: Domain and bucket context objects are prioritized for all types of feeds; this improves usability when remote sites are initiated.

• Retries for Blocked Feeds: Blocked feeds are retried every 20 minutes, but if the definition for a blocked feed is changed, it triggers an immediate attempt with the new definition, which may clear the blockage. (v10.1)