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 InputObject
                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 BuildPath
                By default this command won't attempt to create missing paths, this switch will change the behavious so that it wll
 
            .PARAMETER IgnoreFileChecks
                This switch stops the function from checking for the validity of paths. This can be useful if SQL Server only has read access to the backup area.
                Note, that as we can't check the path you may well end up with errors.
 
            .PARAMETER OutputScriptOnly
                Switch causes only the T-SQL script for the backup to be generated. Will not create any paths if they do now exist
 
            .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: MIT https://opensource.org/licenses/MIT
 
            .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)]
    [Diagnostics.CodeAnalysis.SuppressMessageAttribute("PSAvoidUsingPlainTextForPassword", "")] #For AzureCredential
    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 = $true)]
        [object[]]$InputObject,
        [switch]$CreateFolder,
        [int]$FileCount = 0,
        [switch]$CompressBackup,
        [switch]$Checksum,
        [switch]$Verify,
        [int]$MaxTransferSize,
        [int]$BlockSize,
        [int]$BufferCount,
        [string]$AzureBaseUrl,
        [string]$AzureCredential,
        [switch]$NoRecovery,
        [switch]$BuildPath,
        [switch]$IgnoreFileChecks,
        [switch]$OutputScriptOnly,
        [Alias('Silent')]
        [switch]$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) {
                $InputObject = $server.Databases | Where-Object Name -in $Database
            }
            else {
                $InputObject = $server.Databases | Where-Object Name -ne 'tempdb'
            }

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

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

            if ($InputObject.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
            }

            if ($OutputScriptOnly) {
                $IgnoreFileChecks = $true
            }
        }
    }

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

        Write-Message -Level Verbose -Message "$($InputObject.Count) database to backup"

        foreach ($Database in $InputObject) {
            $ProgressId = Get-Random
            $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 Verbose -Message "Building file name"

            $BackupFinalName = ''
            $FinalBackupPath = @()
            if ('NUL' -eq $BackupFileName) {
                $FinalBackupPath += 'NUL:'
                $IgnoreFileChecks = $true
            }
            elseif ('' -ne $BackupFileName) {
                $File = New-Object System.IO.FileInfo($BackupFileName)
                $BackupFinalName = $file.Name
                $suffix = $file.extension
                if ( '' -ne (Split-Path $BackupFileName)) {
                    Write-Message -Level Verbose -Message "Fully qualified path passed in"
                    $FinalBackupPath += [IO.Path]::GetFullPath($file.DirectoryName)
                }
            }
            else {
                $timestamp = (Get-Date -Format yyyyMMddHHmm)
                Write-Message -Level VeryVerbose -Message "Setting filename"
                $BackupFinalName = "$($dbname)_$timestamp.$suffix"
            }

            Write-Message -Level Verbose -Message "Building backup path"
            if ($FinalBackupPath.Count -eq 0) {
                $FinalBackupPath += $BackupDirectory
            }

            if ($BackupDirectory.Count -eq 1 -and $Filecount -gt 1) {
                for ($i = 0; $i -lt ($Filecount - 1); $i++) {
                    $FinalBackupPath += $FinalBackupPath[0]
                }
            }

            if ($FinalBackupPath.Count -gt 1) {
                $File = New-Object System.IO.FileInfo($BackupFinalName)
                for ($i = 0; $i -lt $FinalBackupPath.Count; $i++) {
                    $FinalBackupPath[$i] = $FinalBackupPath[$i] + "\" + $($File.BaseName) + "-$($i+1)-of-$FileCount.$suffix"
                }
            }
            elseif ($FinalBackupPath[0] -ne 'NUL:') {
                $FinalBackupPath[0] = $FinalBackupPath[0] + "\" + $BackupFinalName
            }

            if ($CreateFolder -and $FinalBackupPath[0] -ne 'NUL:') {
                for ($i = 0; $i -lt $FinalBackupPath.Count; $i++) {
                    $parent = [IO.Path]::GetDirectoryName($FinalBackupPath[$i])
                    $leaf = [IO.Path]::GetFileName($FinalBackupPath[$i])
                    $FinalBackupPath[$i] = [IO.Path]::Combine($parent, $dbname, $leaf)
                }
            }

            if (-not $IgnoreFileChecks) {
                $parentPaths = ($FinalBackupPath | ForEach-Object { Split-Path $_ } | Select-Object -Unique)
                foreach ($parentPath in $parentPaths) {
                    if (-not (Test-DbaSqlPath -SqlInstance $server -Path $parentPath)) {
                        if (($BuildPath -eq $true) -or ($CreateFolder -eq $True)) {
                            $null = New-DbaSqlDirectory -SqlInstance $server -Path $parentPath
                        }
                        else {
                            $failreason += "SQL Server cannot write to the location $parentPath"
                            $failures += $failreason
                            Write-Message -Level Warning -Message "$failreason"
                        }
                    }
                }
            }


            if ('' -eq $AzureBaseUrl -and $BackupDirectory) {
                $FinalBackupPath = $FinalBackupPath | ForEach-Object { [IO.Path]::GetFullPath($_) }
            }


            $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)
                }
                $humanBackupFile = $FinalBackupPath -Join ','
                Write-Message -Level Verbose -Message "Devices added"
                $percent = [Microsoft.SqlServer.Management.Smo.PercentCompleteEventHandler] {
                    Write-Progress -id $ProgressId -activity "Backing up database $dbname to $humanBackupFile" -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 $ProgressId -activity "Backing up database $dbname to $humanBackupFile" -percentcomplete 0 -status ([System.String]::Format("Progress: {0} %", 0))

                try {
                    if ($Pscmdlet.ShouldProcess($server.Name, "Backing up $dbname to $humanBackupFile")) {
                        if ($OutputScriptOnly -ne $True) {
                            $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 $ProgressId -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 $server -DatabaseName DbaVerifyOnly -VerifyOnly -TrustDbBackupHistory -DestinationFilePrefix DbaVerifyOnly
                                if ($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 $FinalBackupPath.Count
                            if ($FinalBackupPath[0] -eq 'NUL:') {
                                $pathresult = "NUL:"
                            }
                            else {
                                $pathresult = (Split-Path $FinalBackupPath | Sort-Object -Unique)
                            }
                            $HeaderInfo | Add-Member -Type NoteProperty -Name BackupFolder -Value $pathresult
                            $HeaderInfo | Add-Member -Type NoteProperty -Name BackupPath -Value ($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
                        }
                        else {
                            $backup.Script($server)
                        }
                    }
                }
                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 $ProgressId -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
        }
    }
}