feat(command/backup): transfers --transfers flag

This commit allows user to control the amount of rclone transfers used during backup.

docs/source/sctool/partials/sctool_backup.yaml

@@ -159,6 +159,10 @@ options:
       usage: |
         Timezone of --cron and --window flag values.
         The default value is taken from this system, namely 'TZ' envvar or '/etc/localtime' file.
+    - name: transfers
+      default_value: "2"
+      usage: |
+        Sets the amount of file transfers to run in parallel when uploading files from a Scylla node to its backup location.
     - name: upload-parallel
       default_value: '[]'
       usage: |

docs/source/sctool/partials/sctool_backup_update.yaml

@@ -160,6 +160,10 @@ options:
       usage: |
         Timezone of --cron and --window flag values.
         The default value is taken from this system, namely 'TZ' envvar or '/etc/localtime' file.
+    - name: transfers
+      default_value: "2"
+      usage: |
+        Sets the amount of file transfers to run in parallel when uploading files from a Scylla node to its backup location.
     - name: upload-parallel
       default_value: '[]'
       usage: |

pkg/command/backup/cmd.go

@@ -32,6 +32,7 @@ type command struct {
 	retention        int
 	retentionDays    int
 	rateLimit        []string
+	transfers        int
 	snapshotParallel []string
 	uploadParallel   []string
 	dryRun           bool
@@ -84,6 +85,7 @@ func (cmd *command) init() {
 	w.Unwrap().IntVar(&cmd.retention, "retention", 7, "")
 	w.Unwrap().IntVar(&cmd.retentionDays, "retention-days", 0, "")
 	w.Unwrap().StringSliceVar(&cmd.rateLimit, "rate-limit", nil, "")
+	w.Unwrap().IntVar(&cmd.transfers, "transfers", 2, "")
 	w.Unwrap().StringSliceVar(&cmd.snapshotParallel, "snapshot-parallel", nil, "")
 	w.Unwrap().StringSliceVar(&cmd.uploadParallel, "upload-parallel", nil, "")
 	w.Unwrap().BoolVar(&cmd.dryRun, "dry-run", false, "")
@@ -144,6 +146,10 @@ func (cmd *command) run(args []string) error {
 		props["rate_limit"] = cmd.rateLimit
 		ok = true
 	}
+	if cmd.Flag("transfers").Changed {
+		props["transfers"] = cmd.transfers
+		ok = true
+	}
 	if cmd.Flag("snapshot-parallel").Changed {
 		props["snapshot_parallel"] = cmd.snapshotParallel
 		ok = true

pkg/command/backup/res.yaml

@@ -19,6 +19,9 @@ rate-limit: |
   The <dc>: part is optional and is only needed when different datacenters require different upload limits.
   Set to 0 for no limit (default 100).
 
+transfers: |
+  Sets the amount of file transfers to run in parallel when uploading files from a Scylla node to its backup location.
+
 snapshot-parallel: |
   A comma-separated list of snapshot parallelism limits in the format `[<dc>:]<limit>`.
   The ``dc`` part is optional and allows for specifying different limits in selected datacenters.