diff --git a/src/tape/media_catalog.rs b/src/tape/media_catalog.rs
new file mode 100644
index 00000000..fbf0a803
--- /dev/null
+++ b/src/tape/media_catalog.rs
@@ -0,0 +1,688 @@
+use std::convert::TryFrom;
+use std::fs::File;
+use std::io::{Write, Read, BufReader};
+use std::path::Path;
+use std::collections::HashMap;
+
+use anyhow::{bail, format_err, Error};
+use endian_trait::Endian;
+
+use proxmox::tools::{
+    Uuid,
+    fs::{
+        fchown,
+        create_path,
+        CreateOptions,
+    },
+    io::{
+        WriteExt,
+        ReadExt,
+    },
+};
+
+use crate::{
+    backup::BackupDir,
+    tape::drive::MediaLabelInfo,
+};
+
+/// The Media Catalog
+///
+/// Stores what chunks and snapshots are stored on a specific media,
+/// including the file position.
+///
+/// We use a simple binary format to store data on disk.
+pub struct MediaCatalog  {
+
+    uuid: Uuid, // BackupMedia uuid
+
+    file: Option<File>,
+
+    pub log_to_stdout: bool,
+
+    current_archive: Option<(Uuid, u64)>,
+
+    last_entry: Option<(Uuid, u64)>,
+
+    chunk_index: HashMap<[u8;32], u64>,
+
+    snapshot_index: HashMap<String, u64>,
+
+    pending: Vec<u8>,
+}
+
+impl MediaCatalog {
+
+    /// Test if a catalog exists
+    pub fn exists(base_path: &Path, uuid: &Uuid) -> bool {
+        let mut path = base_path.to_owned();
+        path.push(uuid.to_string());
+        path.set_extension("log");
+        path.exists()
+    }
+
+    /// Destroy the media catalog (remove all files)
+    pub fn destroy(base_path: &Path, uuid: &Uuid) -> Result<(), Error> {
+
+        let mut path = base_path.to_owned();
+        path.push(uuid.to_string());
+        path.set_extension("log");
+
+        match std::fs::remove_file(path) {
+            Ok(()) => Ok(()),
+            Err(err) if err.kind() == std::io::ErrorKind::NotFound => Ok(()),
+            Err(err) => Err(err.into()),
+        }
+    }
+
+    fn create_basedir(base_path: &Path) -> Result<(), Error> {
+        let backup_user = crate::backup::backup_user()?;
+        let mode = nix::sys::stat::Mode::from_bits_truncate(0o0640);
+        let opts = CreateOptions::new()
+            .perm(mode)
+            .owner(backup_user.uid)
+            .group(backup_user.gid);
+
+        create_path(base_path, None, Some(opts))
+            .map_err(|err: Error| format_err!("unable to create media catalog dir - {}", err))?;
+        Ok(())
+    }
+
+    /// Open a catalog database, load into memory
+    pub fn open(
+        base_path: &Path,
+        uuid: &Uuid,
+        write: bool,
+        create: bool,
+    ) -> Result<Self, Error> {
+
+        let mut path = base_path.to_owned();
+        path.push(uuid.to_string());
+        path.set_extension("log");
+
+        let me = proxmox::try_block!({
+
+            Self::create_basedir(base_path)?;
+
+            let mut file = std::fs::OpenOptions::new()
+                .read(true)
+                .write(write)
+                .create(create)
+                .open(&path)?;
+
+            use std::os::unix::io::AsRawFd;
+
+            let backup_user = crate::backup::backup_user()?;
+            if let Err(err) = fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid)) {
+                bail!("fchown on media catalog {:?} failed - {}", path, err);
+            }
+
+            let mut me = Self {
+                uuid: uuid.clone(),
+                file: None,
+                log_to_stdout: false,
+                current_archive: None,
+                last_entry: None,
+                chunk_index: HashMap::new(),
+                snapshot_index: HashMap::new(),
+                pending: Vec::new(),
+            };
+
+            me.load_catalog(&mut file)?;
+
+            if write {
+                me.file = Some(file);
+            }
+            Ok(me)
+        }).map_err(|err: Error| {
+            format_err!("unable to open media catalog {:?} - {}", path, err)
+        })?;
+
+        Ok(me)
+    }
+
+    /// Creates a temporary, empty catalog database
+    pub fn create_temporary_database(
+        base_path: &Path,
+        label_info: &MediaLabelInfo,
+        log_to_stdout: bool,
+    ) -> Result<Self, Error> {
+
+
+        Self::create_basedir(base_path)?;
+
+        let uuid = &label_info.label.uuid;
+
+        let mut tmp_path = base_path.to_owned();
+        tmp_path.push(uuid.to_string());
+        tmp_path.set_extension("tmp");
+
+        let file = std::fs::OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(&tmp_path)?;
+
+        use std::os::unix::io::AsRawFd;
+
+        let backup_user = crate::backup::backup_user()?;
+        if let Err(err) = fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid)) {
+            bail!("fchown on media catalog {:?} failed - {}", tmp_path, err);
+        }
+
+        let mut me = Self {
+            uuid: uuid.clone(),
+            file: Some(file),
+            log_to_stdout: false,
+            current_archive: None,
+            last_entry: None,
+            chunk_index: HashMap::new(),
+            snapshot_index: HashMap::new(),
+            pending: Vec::new(),
+        };
+
+        me.log_to_stdout = log_to_stdout;
+
+        me.register_label(&label_info.label_uuid, 0)?;
+
+        if let Some((_, ref content_uuid)) = label_info.media_set_label {
+            me.register_label(&content_uuid, 1)?;
+        }
+
+        me.commit()?;
+
+        Ok(me)
+    }
+
+    /// Commit or Abort a temporary catalog database
+    pub fn finish_temporary_database(
+        base_path: &Path,
+        uuid: &Uuid,
+        commit: bool,
+    ) -> Result<(), Error> {
+
+        let mut tmp_path = base_path.to_owned();
+        tmp_path.push(uuid.to_string());
+        tmp_path.set_extension("tmp");
+
+        if commit {
+            let mut catalog_path = tmp_path.clone();
+            catalog_path.set_extension("log");
+
+            if let Err(err) = std::fs::rename(&tmp_path, &catalog_path) {
+                bail!("Atomic rename catalog {:?} failed - {}", catalog_path, err);
+            }
+        } else {
+            std::fs::remove_file(&tmp_path)?;
+        }
+        Ok(())
+    }
+
+    /// Returns the BackupMedia uuid
+    pub fn uuid(&self) -> &Uuid {
+        &self.uuid
+    }
+
+    /// Accessor to content list
+    pub fn snapshot_index(&self) -> &HashMap<String, u64> {
+        &self.snapshot_index
+    }
+
+    /// Commit pending changes
+    ///
+    /// This is necessary to store changes persistently.
+    ///
+    /// Fixme: this should be atomic ...
+    pub fn commit(&mut self) -> Result<(), Error> {
+
+        if self.pending.is_empty() {
+            return Ok(());
+        }
+
+        match self.file {
+            Some(ref mut file) => {
+                file.write_all(&self.pending)?;
+                file.flush()?;
+                file.sync_data()?;
+            }
+            None => bail!("media catalog not writable (opened read only)"),
+        }
+
+        self.pending = Vec::new();
+
+        Ok(())
+    }
+
+    /// Conditionally commit if in pending data is large (> 1Mb)
+    pub fn commit_if_large(&mut self) -> Result<(), Error> {
+        if self.pending.len() > 1024*1024 {
+            self.commit()?;
+        }
+        Ok(())
+    }
+
+    /// Destroy existing catalog, opens a new one
+    pub fn overwrite(
+        base_path: &Path,
+        label_info: &MediaLabelInfo,
+        log_to_stdout: bool,
+    ) ->  Result<Self, Error> {
+
+        let uuid = &label_info.label.uuid;
+
+        let me = Self::create_temporary_database(base_path, &label_info, log_to_stdout)?;
+
+        Self::finish_temporary_database(base_path, uuid, true)?;
+
+        Ok(me)
+    }
+
+    /// Test if the catalog already contain a snapshot
+    pub fn contains_snapshot(&self, snapshot: &str) -> bool {
+        self.snapshot_index.contains_key(snapshot)
+    }
+
+    /// Returns the chunk archive file number
+    pub fn lookup_snapshot(&self, snapshot: &str) -> Option<u64> {
+        self.snapshot_index.get(snapshot).map(|n| *n)
+    }
+
+    /// Test if the catalog already contain a chunk
+    pub fn contains_chunk(&self, digest: &[u8;32]) -> bool {
+        self.chunk_index.contains_key(digest)
+    }
+
+    /// Returns the chunk archive file number
+    pub fn lookup_chunk(&self, digest: &[u8;32]) -> Option<u64> {
+        self.chunk_index.get(digest).map(|n| *n)
+    }
+
+    fn check_register_label(&self, file_number: u64) -> Result<(), Error> {
+
+        if file_number >= 2 {
+            bail!("register label failed: got wrong file number ({} >= 2)", file_number);
+        }
+
+        if self.current_archive.is_some() {
+            bail!("register label failed: inside chunk archive");
+        }
+
+        let expected_file_number = match self.last_entry {
+            Some((_, last_number)) => last_number + 1,
+            None => 0,
+        };
+
+        if file_number != expected_file_number {
+            bail!("register label failed: got unexpected file number ({} < {})",
+                  file_number, expected_file_number);
+        }
+        Ok(())
+    }
+
+    /// Register media labels (file 0 and 1)
+    pub fn register_label(
+        &mut self,
+        uuid: &Uuid, // Uuid form MediaContentHeader
+        file_number: u64,
+    ) -> Result<(), Error> {
+
+        self.check_register_label(file_number)?;
+
+        let entry = LabelEntry {
+            file_number,
+            uuid: *uuid.as_bytes(),
+        };
+
+        if self.log_to_stdout {
+            println!("L|{}|{}", file_number, uuid.to_string());
+        }
+
+        self.pending.push(b'L');
+
+        unsafe { self.pending.write_le_value(entry)?; }
+
+        self.last_entry = Some((uuid.clone(), file_number));
+
+        Ok(())
+    }
+
+    /// Register a chunk
+    ///
+    /// Only valid after start_chunk_archive.
+    pub fn register_chunk(
+        &mut self,
+        digest: &[u8;32],
+    ) -> Result<(), Error> {
+
+        let file_number = match self.current_archive {
+            None => bail!("register_chunk failed: no archive started"),
+            Some((_, file_number)) => file_number,
+        };
+
+        if self.log_to_stdout {
+            println!("C|{}", proxmox::tools::digest_to_hex(digest));
+        }
+
+        self.pending.push(b'C');
+        self.pending.extend(digest);
+
+        self.chunk_index.insert(*digest, file_number);
+
+        Ok(())
+    }
+
+    fn check_start_chunk_archive(&self, file_number: u64) -> Result<(), Error> {
+
+        if self.current_archive.is_some() {
+            bail!("start_chunk_archive failed: already started");
+        }
+
+        if file_number < 2 {
+            bail!("start_chunk_archive failed: got wrong file number ({} < 2)", file_number);
+        }
+
+        let expect_min_file_number = match self.last_entry {
+            Some((_, last_number)) => last_number + 1,
+            None => 0,
+        };
+
+        if file_number < expect_min_file_number {
+            bail!("start_chunk_archive: got unexpected file number ({} < {})",
+                  file_number, expect_min_file_number);
+        }
+
+        Ok(())
+    }
+
+    /// Start a chunk archive section
+    pub fn start_chunk_archive(
+        &mut self,
+        uuid: Uuid, // Uuid form MediaContentHeader
+        file_number: u64,
+    ) -> Result<(), Error> {
+
+        self.check_start_chunk_archive(file_number)?;
+
+        let entry = ChunkArchiveStart {
+            file_number,
+            uuid: *uuid.as_bytes(),
+        };
+
+        if self.log_to_stdout {
+            println!("A|{}|{}", file_number, uuid.to_string());
+        }
+
+        self.pending.push(b'A');
+
+        unsafe { self.pending.write_le_value(entry)?; }
+
+        self.current_archive = Some((uuid, file_number));
+
+        Ok(())
+    }
+
+    fn check_end_chunk_archive(&self, uuid: &Uuid, file_number: u64) -> Result<(), Error> {
+
+        match self.current_archive {
+            None => bail!("end_chunk archive failed: not started"),
+            Some((ref expected_uuid, expected_file_number)) => {
+                if uuid != expected_uuid {
+                    bail!("end_chunk_archive failed: got unexpected uuid");
+                }
+                if file_number != expected_file_number {
+                    bail!("end_chunk_archive failed: got unexpected file number ({} != {})",
+                          file_number, expected_file_number);
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    /// End a chunk archive section
+    pub fn end_chunk_archive(&mut self) -> Result<(), Error> {
+
+        match self.current_archive.take() {
+            None => bail!("end_chunk_archive failed: not started"),
+            Some((uuid, file_number)) => {
+
+                let entry = ChunkArchiveEnd {
+                    file_number,
+                    uuid: *uuid.as_bytes(),
+                };
+
+                if self.log_to_stdout {
+                    println!("E|{}|{}\n", file_number, uuid.to_string());
+                }
+
+                self.pending.push(b'E');
+
+                unsafe { self.pending.write_le_value(entry)?; }
+
+                self.last_entry = Some((uuid, file_number));
+            }
+        }
+
+        Ok(())
+    }
+
+    fn check_register_snapshot(&self, file_number: u64, snapshot: &str) -> Result<(), Error> {
+
+        if self.current_archive.is_some() {
+            bail!("register_snapshot failed: inside chunk_archive");
+        }
+
+        if file_number < 2 {
+            bail!("register_snapshot failed: got wrong file number ({} < 2)", file_number);
+        }
+
+        let expect_min_file_number = match self.last_entry {
+            Some((_, last_number)) => last_number + 1,
+            None => 0,
+        };
+
+        if file_number < expect_min_file_number {
+            bail!("register_snapshot failed: got unexpected file number ({} < {})",
+                  file_number, expect_min_file_number);
+        }
+
+        if let Err(err) = snapshot.parse::<BackupDir>() {
+            bail!("register_snapshot failed: unable to parse snapshot '{}' - {}", snapshot, err);
+        }
+
+        Ok(())
+    }
+
+    /// Register a snapshot
+    pub fn register_snapshot(
+        &mut self,
+        uuid: Uuid, // Uuid form MediaContentHeader
+        file_number: u64,
+        snapshot: &str,
+    ) -> Result<(), Error> {
+
+        self.check_register_snapshot(file_number, snapshot)?;
+
+        let entry = SnapshotEntry {
+            file_number,
+            uuid: *uuid.as_bytes(),
+            name_len: u16::try_from(snapshot.len())?,
+        };
+
+        if self.log_to_stdout {
+            println!("S|{}|{}|{}", file_number, uuid.to_string(), snapshot);
+        }
+
+        self.pending.push(b'S');
+
+        unsafe { self.pending.write_le_value(entry)?; }
+        self.pending.extend(snapshot.as_bytes());
+
+        self.snapshot_index.insert(snapshot.to_string(), file_number);
+
+        self.last_entry = Some((uuid, file_number));
+
+        Ok(())
+    }
+
+    fn load_catalog(&mut self, file: &mut File) -> Result<(), Error> {
+
+        let mut file = BufReader::new(file);
+
+        loop {
+            let mut entry_type = [0u8; 1];
+            match file.read_exact_or_eof(&mut entry_type) {
+                Ok(false) => { /* EOF */ break; }
+                Ok(true) => { /* OK */ }
+                Err(err) => bail!("read failed - {}", err),
+            }
+
+            match entry_type[0] {
+                b'C' => {
+                    let file_number = match self.current_archive {
+                        None => bail!("register_chunk failed: no archive started"),
+                        Some((_, file_number)) => file_number,
+                    };
+                    let mut digest = [0u8; 32];
+                    file.read_exact(&mut digest)?;
+                    self.chunk_index.insert(digest, file_number);
+                }
+                b'A' => {
+                    let entry: ChunkArchiveStart = unsafe { file.read_le_value()? };
+                    let file_number = entry.file_number;
+                    let uuid = Uuid::from(entry.uuid);
+
+                    self.check_start_chunk_archive(file_number)?;
+
+                    self.current_archive = Some((uuid, file_number));
+                }
+                b'E' => {
+                    let entry: ChunkArchiveEnd = unsafe { file.read_le_value()? };
+                    let file_number = entry.file_number;
+                    let uuid = Uuid::from(entry.uuid);
+
+                    self.check_end_chunk_archive(&uuid, file_number)?;
+
+                    self.current_archive = None;
+                    self.last_entry = Some((uuid, file_number));
+                }
+                b'S' => {
+                    let entry: SnapshotEntry = unsafe { file.read_le_value()? };
+                    let file_number = entry.file_number;
+                    let name_len = entry.name_len;
+                    let uuid = Uuid::from(entry.uuid);
+
+                    let snapshot = file.read_exact_allocated(name_len.into())?;
+                    let snapshot = std::str::from_utf8(&snapshot)?;
+
+                    self.check_register_snapshot(file_number, snapshot)?;
+
+                    self.snapshot_index.insert(snapshot.to_string(), file_number);
+
+                    self.last_entry = Some((uuid, file_number));
+                }
+                b'L' => {
+                    let entry: LabelEntry = unsafe { file.read_le_value()? };
+                    let file_number = entry.file_number;
+                    let uuid = Uuid::from(entry.uuid);
+
+                    self.check_register_label(file_number)?;
+
+                    self.last_entry = Some((uuid, file_number));
+                }
+                _ => {
+                    bail!("unknown entry type '{}'", entry_type[0]);
+                }
+            }
+
+        }
+
+        Ok(())
+    }
+}
+
+/// Media set catalog
+///
+/// Catalog for multiple media.
+pub struct MediaSetCatalog  {
+    catalog_list: HashMap<Uuid, MediaCatalog>,
+}
+
+impl MediaSetCatalog {
+
+    /// Creates a new instance
+    pub fn new() -> Self {
+        Self {
+            catalog_list: HashMap::new(),
+        }
+    }
+
+    /// Add a catalog
+    pub fn append_catalog(&mut self, catalog: MediaCatalog) -> Result<(), Error> {
+
+        if self.catalog_list.get(&catalog.uuid).is_some() {
+            bail!("MediaSetCatalog already contains media '{}'", catalog.uuid);
+        }
+
+        self.catalog_list.insert(catalog.uuid.clone(), catalog);
+
+        Ok(())
+    }
+
+    /// Remove a catalog
+    pub fn remove_catalog(&mut self, media_uuid: &Uuid) {
+        self.catalog_list.remove(media_uuid);
+    }
+
+    /// Test if the catalog already contain a snapshot
+    pub fn contains_snapshot(&self, snapshot: &str) -> bool {
+        for catalog in self.catalog_list.values() {
+            if catalog.contains_snapshot(snapshot) {
+                return true;
+            }
+        }
+        false
+    }
+
+    /// Test if the catalog already contain a chunk
+    pub fn contains_chunk(&self, digest: &[u8;32]) -> bool {
+        for catalog in self.catalog_list.values() {
+            if catalog.contains_chunk(digest) {
+                return true;
+            }
+        }
+        false
+    }
+}
+
+// Type definitions for internal binary catalog encoding
+
+#[derive(Endian)]
+#[repr(C)]
+pub struct LabelEntry {
+    file_number: u64,
+    uuid: [u8;16],
+}
+
+#[derive(Endian)]
+#[repr(C)]
+pub struct ChunkArchiveStart {
+    file_number: u64,
+    uuid: [u8;16],
+}
+
+#[derive(Endian)]
+#[repr(C)]
+pub struct ChunkArchiveEnd{
+    file_number: u64,
+    uuid: [u8;16],
+}
+
+#[derive(Endian)]
+#[repr(C)]
+pub struct SnapshotEntry{
+    file_number: u64,
+    uuid: [u8;16],
+    name_len: u16,
+    /* snapshot name follows */
+}
diff --git a/src/tape/mod.rs b/src/tape/mod.rs
index 9bb6bb6e..071029b3 100644
--- a/src/tape/mod.rs
+++ b/src/tape/mod.rs
@@ -1,3 +1,5 @@
+//! Magnetic tape backup
+
 use anyhow::{format_err, Error};
 
 use proxmox::tools::fs::{
@@ -34,6 +36,9 @@ pub use online_status_map::*;
 mod media_pool;
 pub use media_pool::*;
 
+mod media_catalog;
+pub use media_catalog::*;
+
 /// Directory path where we store all tape status information
 pub const TAPE_STATUS_DIR: &str = "/var/lib/proxmox-backup/tape";