Convert TAR.LZO to TAR.BZ2 Online (Trading Fast Decompression for Tighter Ratio)

A Simplified Scan Meeting a Full Block-Sorting Compressor

LZO, the algorithm behind lzop and TAR.LZO, states its own design priority as fast decompression above nearly everything else, and its default lzo1x_1 method deliberately skips the entropy-coding stage most other compressors apply, keeping decoding simple and quick. Bzip2, released by Julian Seward in 1996, takes the opposite approach: it applies the Burrows-Wheeler transform to rearrange each data block so similar byte sequences cluster together, then runs a move-to-front transform and Huffman coding over the rearranged result — a considerably more thorough pipeline than LZO's simplified matching.

Converting TAR.LZO to TAR.BZ2 means fully decompressing lzop's LZO-compressed blocks back into the plain tar byte stream, then feeding that exact same tar data into bzip2's block-sorting pipeline instead. Neither compressor has any concept of individual files; both operate purely on the continuous byte stream tar hands them, so the recompression step treats a ten-file archive and a single large file of equal size identically.

Every bzip2 stream begins with the three ASCII bytes "BZh" followed by a digit from 1 to 9 identifying the block size setting used, a fixed signature any bzip2-aware tool checks first. Lzop's own files start with a completely different nine-byte signature — 0x89 0x4C 0x5A 0x4F 0x00 0x0D 0x0A 0x1A 0x0A — and the two are never interchangeable or mistakable for one another, since a tool reading the wrong signature simply rejects the file outright rather than misinterpreting it.

A Documented, Wide Gap in Both Ratio and Speed

Bzip2 processes data in blocks of up to 900 KB at its maximum -9 setting, sorting each block through the Burrows-Wheeler transform to find and exploit redundancy across a far wider span than LZO's narrower, simplified matching ever attempts. Combined with the entropy-coding stage LZO skips entirely, bzip2 generally produces a noticeably smaller archive than the same content compressed with LZO — often by a wide margin on text-heavy or source-code-style content, where LZO's compression ratio trails furthest behind the more thorough algorithms.

The gap runs sharply in the other direction on speed. LZO's own documentation and independent benchmarks consistently show it decompressing faster than bzip2, gzip, or xz, since bzip2's Burrows-Wheeler transform and its sorting step are considerably more computationally expensive to reverse than LZO's simplified matching. Bzip2 compression itself is also commonly cited as running four to twelve times slower than gzip, and meaningfully slower than LZO's own compression step, which is comparatively simple by design.

Bzip2's block-based design also brings a documented resilience property LZO shares in spirit but implements differently: because each 900 KB block compresses independently, a bzip2 stream can sometimes be partially recovered even if one block is damaged, similar to how lzop's own per-block Adler-32 or CRC-32 checksums let a corrupted block be identified without necessarily losing the rest of the archive, though neither format's checksum mechanism can repair the damage once detected.

What Trading LZO's Speed for Bzip2's Ratio Gains and Costs

• Gain — a meaningfully smaller archive on text-heavy content: bzip2's block-sorting and entropy coding both do work LZO deliberately skips.
• Lose — LZO's fastest-in-class decompression: bzip2 decodes slower than LZO, a real difference if the archive feeds a genuinely time-critical process.
• Lose — LZO's very low CPU and memory overhead: bzip2 needs considerably more processing time and memory than LZO's lighter scan.
• Gain — somewhat broader desktop tool support: bzip2 ships with most current Linux distributions and macOS by default, unlike LZO's much narrower default install base.
• Unchanged — the actual file contents and tar-layer metadata: both compressors are lossless, and neither touches tar's own header fields at all.
• Lose or gain, depending on content: already-compressed media files see little benefit from either algorithm, since neither has much redundancy left to exploit.

Where Each Compressor Is Actually Installed by Default

Reading a TAR.LZO file requires the lzop utility or GNU tar's --lzop flag, since it isn't bundled by default the way more common compressors are, keeping the format concentrated mostly in Linux, Unix, and embedded-systems environments that already have lzop installed for a specific purpose. Bzip2, while not quite as universally default as gzip, ships with most current Linux distributions and macOS as part of the base system or a near-universal default package, and 7-Zip, WinRAR, and PeaZip all read and write TAR.BZ2 on Windows without extra setup.

That gap — LZO's narrow default availability against bzip2's considerably broader one — is a large part of why this specific conversion gets requested: moving content out of a format that needs a purpose-installed tool almost everywhere outside Linux and into one that's already present or trivially installable on far more systems.

Programming language support follows a similar pattern: Python's standard library includes a bz2 module for reading and writing bzip2 streams directly with no extra package, while working with LZO-compressed data generally requires a separate, less commonly maintained third-party binding. This matters directly for anyone automating this conversion as part of a script rather than running it interactively, since bzip2 support can usually be assumed available in a modern language runtime.

Real Reports From Switching Between These Two Algorithms

A recurring, documented complaint involves an embedded-systems developer converting a firmware or configuration archive from TAR.LZO to TAR.BZ2 for easier long-term storage, then finding the compression step itself takes noticeably longer than the original LZO build did — this isn't a malfunction, it's the expected cost of bzip2's Burrows-Wheeler transform doing meaningfully more work than LZO's simplified matching ever attempted.

A second pattern involves the opposite direction specifically: a firmware image converted to TAR.BZ2 for archival turning out unusable for actual deployment, since a device's bootloader written to decompress LZO-compressed data has no bzip2 decoder in its limited firmware at all — in these cases, the archived long-term copy and the version actually flashed onto hardware legitimately need to stay in two different formats.

A third report involves scripts hardcoded around a specific tar flag — one written to call tar with --lzop for extraction fails outright against a TAR.BZ2 file rebuilt from that same content, since the two compression methods aren't interchangeable at the command level, and any automation built around the original format needs updating to expect -j or --bzip2 instead.

A fourth pattern shows up around memory-constrained build environments: bzip2's compression at its maximum -9 setting needs roughly eight times the block size in working memory according to its own documented design, a real, higher resource footprint than LZO's lighter scan requires, which occasionally forces a lower bzip2 compression level on machines with limited RAM even after the switch away from LZO's minimal memory needs.

LZO's Speed Priority Set Against Bzip2's Block-Sorting Ratio

Questions About Rebuilding an LZO Tarball With Bzip2 Compression

Will my archive get smaller after converting TAR.LZO to TAR.BZ2?
Usually, often noticeably, since bzip2's block-sorting and entropy coding both do work that LZO's simplified matching deliberately skips to keep decompression fast.

Why does converting to TAR.BZ2 take so much longer than the original LZO compression did?
Bzip2's Burrows-Wheeler transform and sorting step are considerably more computationally demanding than LZO's simplified scan, which is a real, expected cost rather than a problem with the conversion itself.

Is bzip2 easier to find installed than lzop?
Generally, yes. Bzip2 ships with most current Linux distributions and macOS by default, while lzop typically has to be installed separately even on systems that already have bzip2 available.

Should I convert a firmware image meant for a device's bootloader to bzip2?
Not for the deployed version. If the bootloader expects LZO-compressed data directly, converting the deployed image to bzip2 will likely make it unusable on that specific hardware.

Does this conversion change any of the actual files inside the archive?
No. Both LZO and bzip2 are lossless compression methods, so every file extracted afterward is byte-for-byte identical to what was originally inside the TAR.LZO archive.

Can a damaged TAR.BZ2 file still be partially recovered, like a TAR.LZO can?
Sometimes, in both cases, though differently. Bzip2's independent 900 KB blocks can sometimes survive a nearby block's corruption, and lzop's own per-block checksums serve a similar detection role, though neither format can repair the damage once it's found.

Is there a middle ground between LZO's speed and bzip2's ratio?
Gzip's DEFLATE sits roughly between the two on both measures, compressing tighter than LZO but faster than bzip2, which is one reason it remains the most common default among tar-based compression options.