functions/Backup-DbaDatabase.ps1

function Backup-DbaDatabase {
    <#
            .SYNOPSIS
                Backup one or more SQL Sever databases from a single SQL Server SqlInstance.
 
            .DESCRIPTION
                Performs a backup of a specified type of 1 or more databases on a single SQL Server Instance. These backups may be Full, Differential or Transaction log backups.
 
            .PARAMETER SqlInstance
                The SQL Server instance hosting the databases to be backed up.
 
            .PARAMETER SqlCredential
                Credentials to connect to the SQL Server instance if the calling user doesn't have permission.
 
            .PARAMETER Database
                The database(s) to process. This list is auto-populated from the server. If unspecified, all databases will be processed.
 
            .PARAMETER ExcludeDatabase
                The database(s) to exclude. This list is auto-populated from the server.
 
            .PARAMETER BackupFileName
                The name of the file to backup to. This is only accepted for single database backups.
                If no name is specified then the backup files will be named DatabaseName_yyyyMMddHHmm (i.e. "Database1_201714022131") with the appropriate extension.
 
                If the same name is used repeatedly, SQL Server will add backups to the same file at an incrementing position.
 
                SQL Server needs permissions to write to the specified location. Path names are based on the SQL Server (C:\ is the C drive on the SQL Server, not the machine running the script).
 
            .PARAMETER BackupDirectory
                Path in which to place the backup files. If not specified, the backups will be placed in the default backup location for SqlInstance.
                If multiple paths are specified, the backups will be striped across these locations. This will overwrite the FileCount option.
 
                If the path does not exist, Sql Server will attempt to create it. Folders are created by the Sql Instance, and checks will be made for write permissions.
 
                File Names with be suffixed with x-of-y to enable identifying striped sets, where y is the number of files in the set and x ranges from 1 to y.
 
            .PARAMETER CopyOnly
                If this switch is enabled, CopyOnly backups will be taken. By default function performs a normal backup, these backups interfere with the restore chain of the database. CopyOnly backups will not interfere with the restore chain of the database.
 
                For more details please refer to this MSDN article - https://msdn.microsoft.com/en-us/library/ms191495.aspx
 
            .PARAMETER Type
                The type of SQL Server backup to perform. Accepted values are "Full", "Log", "Differential", "Diff", "Database"
 
            .PARAMETER FileCount
                This is the number of striped copies of the backups you wish to create. This value is overwritten if you specify multiple Backup Directories.
 
            .PARAMETER CreateFolder
                If this switch is enabled, each database will be backed up into a separate folder on each of the paths specified by BackupDirectory.
 
            .PARAMETER CompressBackup
                If this switch is enabled, the function will try to perform a compressed backup if supported by the version and edition of SQL Server. Otherwise, this function will use the server's default setting for compression.
 
            .PARAMETER MaxTransferSize
                Sets the size of the unit of transfer. Values must be a multiple of 64kb.
 
            .PARAMETER Blocksize
                Specifies the block size to use. Must be one of 0.5KB, 1KB, 2KB, 4KB, 8KB, 16KB, 32KB or 64KB. This can be specified in bytes.
                Refer to https://msdn.microsoft.com/en-us/library/ms178615.aspx for more detail
 
            .PARAMETER BufferCount
                Number of I/O buffers to use to perform the operation.
                Refer to https://msdn.microsoft.com/en-us/library/ms178615.aspx for more detail
 
            .PARAMETER Checksum
                If this switch is enabled, the backup checksum will be calculated.
 
            .PARAMETER Verify
                If this switch is enabled, the backup will be verified by running a RESTORE VERIFYONLY against the SqlInstance
 
            .PARAMETER DatabaseCollection
                Internal parameter
 
            .PARAMETER AzureBaseUrl
                The URL to the basecontainer of an Azure storage account to write backups to.
 
                If specified, the only other parameters than can be used are "NoCopyOnly", "Type", "CompressBackup", "Checksum", "Verify", "AzureCredential", "CreateFolder".
 
            .PARAMETER AzureCredential
                The name of the credential on the SQL instance that can write to the AzureBaseUrl.
 
            .PARAMETER NoRecovery
                This is passed in to perform a tail log backup if needed
 
            .PARAMETER EnableException
                By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
                This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
                Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
 
            .PARAMETER WhatIf
                If this switch is enabled, no actions are performed but informational messages will be displayed that explain what would happen if the command were to run.
 
            .PARAMETER Confirm
                If this switch is enabled, you will be prompted for confirmation before executing any operations that change state.
 
            .NOTES
                Tags: DisasterRecovery, Backup, Restore
                Author: Stuart Moore (@napalmgram), stuart-moore.com
 
                Website: https://dbatools.io
                Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
                License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
            .EXAMPLE
                Backup-DbaDatabase -SqlInstance Server1 -Database HR, Finance
 
                This will perform a full database backup on the databases HR and Finance on SQL Server Instance Server1 to Server1's default backup directory.
 
            .EXAMPLE
                Backup-DbaDatabase -SqlInstance sql2016 -BackupDirectory C:\temp -Database AdventureWorks2014 -Type Full
 
                Backs up AdventureWorks2014 to sql2016's C:\temp folder.
 
            .EXAMPLE
                Backup-DbaDatabase -SqlInstance sql2016 -AzureBaseUrl https://dbatoolsaz.blob.core.windows.net/azbackups/ -AzureCredential dbatoolscred -Type Full -CreateFolder
 
                Performs a full backup of all databases on the sql2016 instance to their own containers under the https://dbatoolsaz.blob.core.windows.net/azbackups/ container on Azure blog storage using the sql credential "dbatoolscred" registered on the sql2016 instance.
    #>

    [CmdletBinding(DefaultParameterSetName = "Default", SupportsShouldProcess = $true)]
    param (
        [parameter(ParameterSetName = "Pipe", Mandatory = $true)]
        [DbaInstanceParameter]$SqlInstance,
        [PSCredential]$SqlCredential,
        [Alias("Databases")]
        [object[]]$Database,
        [object[]]$ExcludeDatabase,
        [string[]]$BackupDirectory,
        [string]$BackupFileName,
        [switch]$CopyOnly,
        [ValidateSet('Full', 'Log', 'Differential', 'Diff', 'Database')]
        [string]$Type = 'Database',
        [parameter(ParameterSetName = "NoPipe", Mandatory = $true, ValueFromPipeline = $true)]
        [object[]]$DatabaseCollection,
        [switch]$CreateFolder,
        [int]$FileCount = 0,
        [switch]$CompressBackup,
        [switch]$Checksum,
        [switch]$Verify,
        [int]$MaxTransferSize,
        [int]$BlockSize,
        [int]$BufferCount,
        [string]$AzureBaseUrl,
        [string]$AzureCredential,
        [switch]$NoRecovery,
        [switch][Alias('Silent')]$EnableException
    )

    begin {

        if ($SqlInstance.length -ne 0) {
            Write-Message -Level Verbose -Message "Connecting to $SqlInstance"
            try {
                $Server = Connect-SqlInstance -SqlInstance $SqlInstance -SqlCredential $SqlCredential
            }
            catch {
                Write-Message -Level Warning -Message "Cannot connect to $SqlInstance"
                continue
            }

            if ($Database) {
                $DatabaseCollection = $server.Databases | Where-Object { $_.Name -in $Database }
            }
            else {
                $DatabaseCollection = $server.Databases | Where-object { $_.Name -ne 'tempdb' }
            }

            if ($ExcludeDatabase) {
                $DatabaseCollection = $DatabaseCollection | Where-Object Name -notin $ExcludeDatabase
            }

            if ($BackupDirectory.count -gt 1) {
                Write-Message -Level Verbose -Message "Multiple Backup Directories, striping"
                $Filecount = $BackupDirectory.count
            }

            if ($DatabaseCollection.count -gt 1 -and $BackupFileName -ne '') {
                Write-Message -Level Warning -Message "1 BackupFile specified, but more than 1 database."
                break
            }

            if (($MaxTransferSize % 64kb) -ne 0 -or $MaxTransferSize -gt 4mb) {
                Write-Message -Level Warning -Message "MaxTransferSize value must be a multiple of 64kb and no greater than 4MB"
                break
            }
            if ($BlockSize) {
                if ($BlockSize -notin (0.5kb, 1kb, 2kb, 4kb, 8kb, 16kb, 32kb, 64kb)) {
                    Write-Message -Level Warning -Message "Block size must be one of 0.5kb,1kb,2kb,4kb,8kb,16kb,32kb,64kb"
                    break
                }
            }
            if ('' -ne $AzureBaseUrl) {
                if ($null -eq $AzureCredential) {
                    Stop-Function -Message "You must provide the credential name for the Azure Storage Account"
                    break
                }
                $AzureBaseUrl = $AzureBaseUrl.Trim("/")
                $FileCount = 1
                $BackupDirectory = $AzureBaseUrl
            }
        }
    }

    process {
        if (!$SqlInstance -and !$DatabaseCollection) {
            Write-Message -Level Warning -Message "You must specify a server and database or pipe some databases"
            continue
        }

        Write-Message -Level Verbose -Message "$($DatabaseCollection.count) database to backup"

        ForEach ($Database in $databasecollection) {
            $failures = @()
            $dbname = $Database.name

            if ($dbname -eq "tempdb") {
                Write-Message -Level Warning -Message "Backing up tempdb not supported"
                continue
            }

            if ('Normal' -notin ($Database.Status -split ',')) {
                Write-Message -Level Warning -Message "Database status not Normal. $dbname skipped."
                continue
            }

            if ($Database.DatabaseSnapshotBaseName) {
                Write-Message -Level Warning -Message "Backing up snapshots not supported. $dbname skipped."
                continue
            }

            if ($null -eq $server) { $server = $Database.Parent }

            Write-Message -Level Verbose -Message "Backup database $database"

            if ($null -eq $Database.RecoveryModel) {
                $Database.RecoveryModel = $server.databases[$Database.Name].RecoveryModel
                Write-Message -Level Verbose -Message "$dbname is in $($Database.RecoveryModel) recovery model"
            }

            # Fixes one-off cases of StackOverflowException crashes, see issue 1481
            $dbRecovery = $Database.RecoveryModel.ToString()
            if ($dbRecovery -eq 'Simple' -and $Type -eq 'Log') {
                $failreason = "$database is in simple recovery mode, cannot take log backup"
                $failures += $failreason
                Write-Message -Level Warning -Message "$failreason"
            }

            $lastfull = $database.Refresh().LastBackupDate.Year

            if ($Type -notin @("Database", "Full") -and $lastfull -eq 1) {
                $failreason = "$database does not have an existing full backup, cannot take log or differentialbackup"
                $failures += $failreason
                Write-Message -Level Warning -Message "$failreason"
            }

            if ($CopyOnly -ne $True) {
                $CopyOnly = $false
            }

            $server.ConnectionContext.StatementTimeout = 0
            $backup = New-Object Microsoft.SqlServer.Management.Smo.Backup
            $backup.Database = $Database.Name
            $Suffix = "bak"

            if ($CompressBackup) {
                if ($server.Edition -like 'Express*' -or ($server.VersionMajor -eq 10 -and $server.VersionMinor -eq 0 -and $server.Edition -notlike '*enterprise*') -or $server.VersionMajor -lt 10) {
                    Write-Message -Level Warning -Message "Compression is not supported with this version/edition of Sql Server"
                }
                else {
                    Write-Message -Level Verbose -Message "Compression enabled"
                    $backup.CompressionOption = 1
                }
            }

            if ($Checksum) {
                $backup.Checksum = $true
            }

            if ($type -in 'diff', 'differential') {
                Write-Message -Level VeryVerbose -Message "Creating differential backup"
                $SMOBackuptype = "Database"
                $backup.Incremental = $true
                $outputType = 'Differential'
            }
            $Backup.NoRecovery = $False
            if ($Type -eq "Log") {
                Write-Message -Level VeryVerbose -Message "Creating log backup"
                $Suffix = "trn"
                $OutputType = 'Log'
                $SMOBackupType = 'Log'
                $Backup.NoRecovery = $NoRecovery
            }

            if ($type -in 'Full', 'Database') {
                Write-Message -Level VeryVerbose -Message "Creating full backup"
                $SMOBackupType = "Database"
                $OutputType = 'Full'
            }

            $backup.CopyOnly = $copyonly
            $backup.Action = $SMOBackupType
            if ('' -ne $AzureBaseUrl) {
                $backup.CredentialName = $AzureCredential
            }

            Write-Message -Level VeryVerbose -Message "Sorting Paths"

            #If a backupfilename has made it this far, use it
            $FinalBackupPath = @()

            if ($BackupFileName) {
                if ($BackupFileName -notlike "*:*") {
                    if (!$BackupDirectory) {
                        $BackupDirectory = $server.BackupDirectory
                    }

                    $BackupFileName = "$BackupDirectory\$BackupFileName" # removed auto suffix
                }

                Write-Message -Level Verbose -Message "Single db and filename"

                if (Test-DbaSqlPath -SqlInstance $server -Path (Split-Path $BackupFileName)) {
                    $FinalBackupPath += $BackupFileName
                }
                else {
                    $failreason = "SQL Server cannot write to the location $(Split-Path $BackupFileName)"
                    $failures += $failreason
                    Write-Message -Level Warning -Message "$failreason"
                }
            }
            else {
                if (!$BackupDirectory) {
                    $BackupDirectory += $server.BackupDirectory
                }

                $timestamp = (Get-Date -Format yyyyMMddHHmm)
                Write-Message -Level VeryVerbose -Message "Setting filename"
                $BackupFileName = "$($dbname)_$timestamp"
                if ('' -ne $AzureBaseUrl) {
                    Write-Message -Level VeryVerbose -Message "Azure div"
                    $PathDivider = "/"
                }
                else {
                    $PathDivider = "\"
                }
                Foreach ($path in $BackupDirectory) {
                    if ($CreateFolder) {
                        $Path = $path + $PathDivider + $Database.name
                        Write-Message -Level Verbose -Message "Creating Folder $Path"
                        if ($Pscmdlet.ShouldProcess($server.Name, "Creating folder $path")) {
                            if (((New-DbaSqlDirectory -SqlInstance $server -SqlCredential $SqlCredential -Path $path).Created -eq $false) -and '' -eq $AzureBaseUrl) {
                                $failreason = "Cannot create or write to folder $path"
                                $failures += $failreason
                                Write-Message -Level Warning -Message "$failreason"
                            }
                            else {
                                $FinalBackupPath += "$path$PathDivider$BackupFileName.$suffix"
                            }
                        }
                    }
                    else {
                        $FinalBackupPath += "$path$PathDivider$BackupFileName.$suffix"
                    }
                    <#
                        The code below attempts to create the directory even when $CreateFolder -- was it supposed to be Test-DbaSqlPath?
                        else
                        {
                            if ((New-DbaSqlDirectory -SqlInstance $server -SqlCredential $SqlCredential -Path $path).Created -eq $false)
                            {
                                $failreason = "Cannot create or write to folder $path"
                                $failures += $failreason
                                Write-Message -Level Warning -Message "$failreason"
                            }
                            $FinalBackupPath += "$path\$BackupFileName.$suffix"
                        }
                        #>

                }
            }

            if ('' -eq $AzureBaseUrl) {
                $file = New-Object System.IO.FileInfo($FinalBackupPath[0])
            }
            $suffix = $file.Extension

            if ($FileCount -gt 1 -and $FinalBackupPath.count -eq 1) {
                Write-Message -Level Verbose -Message "Striping for Filecount of $filecount"
                $stripes = $filecount

                for ($i = 2; $i -lt $stripes + 1; $i++) {
                    $FinalBackupPath += $FinalBackupPath[0].Replace("$suffix", "-$i-of-$stripes$($suffix)")
                }
                $FinalBackupPath[0] = $FinalBackupPath[0].Replace("$suffix", "-1-of-$stripes$($suffix)")

            }
            elseif ($FinalBackupPath.count -gt 1) {
                Write-Message -Level Verbose -Message "String for Backup path count of $($FinalBackupPath.count)"
                $stripes = $FinalbackupPath.count
                for ($i = 1; $i -lt $stripes + 1; $i++) {
                    $FinalBackupPath[($i - 1)] = $FinalBackupPath[($i - 1)].Replace($suffix, "-$i-of-$stripes$($suffix)")
                }
            }

            $script = $null
            $backupComplete = $false

            if (!$failures) {
                $filecount = $FinalBackupPath.count

                foreach ($backupfile in $FinalBackupPath) {
                    $device = New-Object Microsoft.SqlServer.Management.Smo.BackupDeviceItem
                    if ('' -ne $AzureBaseUrl) {
                        $device.DeviceType = "URL"
                    }
                    else {
                        $device.DeviceType = "File"
                    }
                    $device.Name = $backupfile
                    $backup.Devices.Add($device)
                }

                Write-Message -Level Verbose -Message "Devices added"
                $percent = [Microsoft.SqlServer.Management.Smo.PercentCompleteEventHandler] {
                    Write-Progress -id 1 -activity "Backing up database $dbname to $backupfile" -percentcomplete $_.Percent -status ([System.String]::Format("Progress: {0} %", $_.Percent))
                }
                $backup.add_PercentComplete($percent)
                $backup.PercentCompleteNotification = 1
                $backup.add_Complete($complete)

                if ($MaxTransferSize) {
                    $backup.MaxTransferSize = $MaxTransferSize
                }
                if ($BufferCount) {
                    $backup.BufferCount = $BufferCount
                }
                if ($BlockSize) {
                    $backup.Blocksize = $BlockSize
                }

                Write-Progress -id 1 -activity "Backing up database $dbname to $backupfile" -percentcomplete 0 -status ([System.String]::Format("Progress: {0} %", 0))

                try {
                    if ($Pscmdlet.ShouldProcess($server.Name, "Backing up $dbname to $backupfile")) {
                        $Filelist = @()
                        $FileList += $server.Databases[$dbname].FileGroups.Files | Select-Object @{ Name = "FileType"; Expression = { "D" } }, @{ Name = "Type"; Expression = { "D" } }, @{ Name = "LogicalName"; Expression = { $_.Name } }, @{ Name = "PhysicalName"; Expression = { $_.FileName } }
                        $FileList += $server.Databases[$dbname].LogFiles | Select-Object @{ Name = "FileType"; Expression = { "L" } }, @{ Name = "Type"; Expression = { "L" } }, @{ Name = "LogicalName"; Expression = { $_.Name } }, @{ Name = "PhysicalName"; Expression = { $_.FileName } }

                        $backup.SqlBackup($server)
                        $script = $backup.Script($server)
                        Write-Progress -id 1 -activity "Backing up database $dbname to $backupfile" -status "Complete" -Completed
                        $BackupComplete = $true
                        if ($server.VersionMajor -eq '8') {
                            $HeaderInfo = Get-BackupAncientHistory -SqlInstance $server -Database $dbname
                        }
                        else {
                            $HeaderInfo = Get-DbaBackupHistory -SqlInstance $server -Database $dbname -Last -IncludeCopyOnly | Sort-Object -Property End -Descending | Select-Object -First 1
                        }
                        $Verified = $false
                        if ($Verify) {
                            $verifiedresult = [PSCustomObject]@{
                                SqlInstance          = $server.name
                                DatabaseName         = $dbname
                                BackupComplete       = $BackupComplete
                                BackupFilesCount     = $FinalBackupPath.count
                                BackupFile           = (Split-Path $FinalBackupPath -leaf)
                                BackupFolder         = (Split-Path $FinalBackupPath | Sort-Object -Unique)
                                BackupPath           = ($FinalBackupPath | Sort-Object -Unique)
                                Script               = $script
                                Notes                = $failures -join (',')
                                FullName             = ($FinalBackupPath | Sort-Object -Unique)
                                FileList             = $FileList
                                SoftwareVersionMajor = $server.VersionMajor
                                Type                 = $outputType
                                FirstLsn             = $HeaderInfo.FirstLsn
                                DatabaseBackupLsn    = $HeaderInfo.DatabaseBackupLsn
                                CheckPointLsn        = $HeaderInfo.CheckPointLsn
                                LastLsn              = $HeaderInfo.LastLsn
                                BackupSetId          = $HeaderInfo.BackupSetId
                                LastRecoveryForkGUID = $HeaderInfo.LastRecoveryForkGUID
                            } | Restore-DbaDatabase -SqlInstance $server -SqlCredential $SqlCredential -DatabaseName DbaVerifyOnly -VerifyOnly -TrustDbBackupHistory -DestinationFilePrefix DbaVerifyOnly
                            if ($verifiedResult[0] -eq "Verify successful") {
                                $failures += $verifiedResult[0]
                                $Verified = $true
                            }
                            else {
                                $failures += $verifiedResult[0]
                                $Verified = $false
                            }
                        }
                        $HeaderInfo | Add-Member -Type NoteProperty -Name BackupComplete -Value $BackupComplete
                        $HeaderInfo | Add-Member -Type NoteProperty -Name BackupFile -Value (Split-Path $FinalBackupPath -leaf)
                        $HeaderInfo | Add-Member -Type NoteProperty -Name BackupFilesCount -Value $FinalBackupPath.count
                        $HeaderInfo | Add-Member -Type NoteProperty -Name BackupFolder -Value (Split-Path $FinalBackupPath | Sort-Object -Unique)
                        $HeaderInfo | Add-Member -Type NoteProperty -Name BackupPath -Value ($FinalBackupPath | Sort-Object -Unique)
                        $HeaderInfo | Add-Member -Type NoteProperty -Name DatabaseName -Value $dbname
                        $HeaderInfo | Add-Member -Type NoteProperty -Name Notes -Value ($failures -join (','))
                        $HeaderInfo | Add-Member -Type NoteProperty -Name Script -Value $script
                        $HeaderInfo | Add-Member -Type NoteProperty -Name Verified -Value $Verified
                    }
                }
                catch {
                    if ($NoRecovery -and ($_.Exception.InnerException.InnerException.InnerException -like '*cannot be opened. It is in the middle of a restore.')) {
                        Write-Message -Message "Exception thrown by db going into restoring mode due to recovery" -Leve Verbose
                    }
                    else {
                        Write-Progress -id 1 -activity "Backup" -status "Failed" -completed
                        Stop-Function -message "Backup Failed: $($_.Exception.Message)" -EnableException $EnableException -ErrorRecord $_
                        $BackupComplete = $false
                    }
                }
            }
            $OutputExclude = 'FullName', 'FileList', 'SoftwareVersionMajor'
            if ($failures.count -eq 0) {
                $OutputExclude += ('Notes', 'FirstLsn', 'DatabaseBackupLsn', 'CheckpointLsn', 'LastLsn', 'BackupSetId', 'LastRecoveryForkGuid')
            }
            $headerinfo | Select-DefaultView -ExcludeProperty $OutputExclude
            $BackupFileName = $null
        }
    }
}