backup-bench

Quick and dirty backup tool benchmark with reproducible results

** This is a one page entry with benchmarks (see below), previous versions are available via git versioning.**

What

This repo aims to compare different backup solutions among:

• borg backup
• bupstash
• restic
• kopia
• duplicacy
• your tool (PRs to support new backup tools are welcome)

The idea is to have a script that executes all backup programs on the same datasets.

We'll use a quite big (and popular) git repo as first dataset so results can be reproduced by checking out branches (and ignoring .git directory). I'll also use another (not public) dataset which will be some qcow2 files which are in use.

Time spent by the backup program is measured by the script so we get as accurate as possible results (time is measured from process beginning until process ends, with a 1 second granularity).

While backups are done, cpu/memory/disk metrics are saved so we know how "resource hungry" a backup program can be.

All backup programs are setup to use SSH in order to compare their performance regardless of the storage backend.

When available, we'll tune the encryption algorithm depending on the results of a benchmark. For instance, kopia has a kopia benchmark compression --data-file=/some/big/data/file option to find out which compression / crypto works best on the current architecture. This is REALLY NICE TO HAVE when choices need to be made, aware of current architecture. As of the current tests, Borg v2.0.0-b1 also has a borg benchmark cpu option.

Why

I am currently using multiple backup programs to achieve my needs. As of today, I use Graham Keeling's burp https://github.com/grke/burp to backup windows machines, and borg backup to backup QEMU VM images. Graham decided to remove its deduplication (protocol 2) and stick with rsync based backups (protocol 1), which isn't compatible with my backup strategies. I've also tried out bupstash which I found to be quite quick, but which produces bigger backups remotely when dealing with small files (probably because of the chunk size?).

Anyway, I am searching for a good allrounder, so I decided to give all the deduplicating backup solutions a try, and since I am configuring them all, I thought why not make my results available to anyone, with a script so everything can be reproduced easily.

As of today I use the script on my lab hypervisor, which runs AlmaLinux 8.6. The script should run on other distros, although I didn't test it.

I'll try to be as little biased as possible when doing my backup tests. If you feel that I didn't give a specific program enough attention, feel free to open an issue.

In depth comparison of backup solutions

Last update: 03 October 2022

Backup software	Version
borg	1.2.2
borg beta	2.0.0b2
restic	0.14.0
kopia	0.12.0
bupstash	0.11.1
duplicacy	2.7.2

The following list is my personal shopping list when it comes to backup solutions, and might not be complete, you're welcome to provide PRs to update it. ;)

Goal	Functionality	borg	restic	kopia	bupstash	duplicacy
Reliability	Redundant index copies	?	?	Yes	yes, redundant + sync	No indexes used
Reliability	Continue restore on bad blocks in repository	?	?	Yes (can ignore errors when restoring)	No	Yes, erasure coding
Reliability	Data checksumming	Yes (CRC & HMAC)	?	No (Reed–Solomon in the works)	HMAC	Yes
Reliability	Backup coherency (detecting in flight file changes while backing up)	Yes	Yes	?	No	?
Restoring Data	Backup mounting as filesystem	Yes	Yes	Yes	No	No
File management	File includes / excludes bases on regexes	Yes	?	?	?	Yes
File management	Supports backup XATTRs	Yes	?	No	Yes	?
File management	Supports backup ACLs	Yes	?	No	Yes	?
File management	Supports hardlink identification (no multiple stored hardlinked files	No (borg2 will	Yes	No	Yes	No
File management	Supports sparse files (thin provisionned files on disk)	Yes	Yes	Yes	Yes	?
File management	Can exclude CACHEDIR.TAG(3) directories	Yes	Yes	Yes	Yes	No
Dedup & compression efficiency	Is data compressed	Yes	Yes	Yes	Yes	Yes
Dedup & compression efficiency	Uses newer compression algorithms (ie zstd)	Yes	Yes	Yes	Yes	Yes
Dedup & compression efficiency	Can files be excluded from compression by extension	?	No	Yes	No	No
Dedup & compression efficiency	Is data deduplicated	Yes	Yes	Yes	Yes	Yes
Platform support	Programming lang	Python	Go	Go	Rust	Go
Platform support	Unix Prebuilt binaries	Yes	Yes	Yes	No	Yes
Platform support	Windows support	Yes (WSL)	Yes	Yes	No	Yes
Platform support	Windows first class support (PE32 binary)	No	Yes	Yes	No	Yes
Platform support	Unix snapshot support where snapshot path prefix is removed	?	?	?	?	?
Platform support	Windows VSS snapshot support where snapshot path prefix is removed	No	Yes	No, but pre-/post hook VSS script provided	No	Yes
WAN Support	Can backups be sent to a remote destination without keeping a local copy	Yes	Yes	Yes	Yes	Yes
WAN Support	What other remote backends are supported ?	rclone	(1)	(2)	None	(1)
Security	Are encryption protocols secure (AES-256-GCM / PolyChaCha / etc ) ?	Yes, AES-256-GCM	Yes, AES-256	Yes, AES-256-GCM or Chacha20Poly1305	Yes, Chacha20Poly1305	Yes, AES-256-GCM
Security	Are metadatas encrypted too ?	?	Yes	?	Yes	Yes
Security	Can encrypted / compressed data be guessed (CRIME/BREACH style attacks)?	No	No	?	No (4)	?
Security	Can a compromised client delete backups?	No (append mode)	No (append mode)	Supports optional object locking	No (ssh restriction )	No pubkey + immutable targets
Security	Can a compromised client restore encrypted data?	Yes	?	?	No	No pubkey
Security	Are pull backup scenarios possible?	Yes	No	No	No, planned	?
Misc	Does the backup software support pre/post execution hooks?	?	?	Yes	No	Yes
Misc	Does the backup software provide an API for their client ?	Yes (JSON cmd)	No, but REST API on server	No, but REST API on server	No	No
Misc	Does the backup sofware provide an automatic GFS system ?	Yes	Yes	Yes	No	?
Misc	Does the backup sofware provide a crypto benchmark ?	No, available in beta	No	Yes	Undocumented	No, generic benchmark
Misc	Can a repo be synchronized to another repo ?	?	?	Yes	Yes	Yes

• (1) SFTP/S3/Wasabi/B2/Aliyun/Swift/Azure/Google Cloud
• (2) SFTP/Google Cloud/S3 and S3-compatible storage like Wasabi/B2/Azure/WebDav/rclone*
• (3) see https://bford.info/cachedir/
• (4) For bupstash, CRIME/BREACH style attacks are mitigated if you disable read access for backup clients, and keep decryption keys off server.

A quick word about backup coherence:

While some backup tools might detect filesysetm changes inflight, it's usually the burden of a snapshot system (zfs, bcachefs, lvm, btrfs, vss...) to provide the backup program a reliable static version of the filesystem. Still it's a really nice to have in order to detect problems on backups without those snapshot aware tools, like plain XFS/EXT4 partitions.

Results

2022-10-02

Used system specs

• Source system: Xeon E3-1275, 64GB RAM, 2x SSD 480GB (for git dataset and local target), 2x4TB disks 7.2krpm (for bigger dataset), using XFS, running AlmaLinux 8.6

• Remote target system: AMD Turion(tm) II Neo N54L Dual-Core Processor (yes, this is old), 6GB RAM, 2x4TB WD RE disks 7.2krpm using ZFS 2.1.5, 1x 1TB WD Blue using XFS, running AlmaLinux 8.6

• Target system has a XFS filesystem as target for the linux kernel backup tests

• Target system has a ZFS filesystem as target for the qemu backup tests. ZFS has been configured as follows:

  • zfs set xattr=off backup
  • zfs set compression=off backup # Since we already compress, we don't want to add another layer here
  • zfs set atime=off backup
  • zfs set recordsize=1M backup # This could be tuned as per backup program...

source data for local and remote multiple git repo versions backup benchmarks

Linux kernel sources, initial git checkout v5.19, then changed to v5.18, 4.18 and finally v3.10 for the last run. Initial git directory totals 4.1GB, for 5039 directories and 76951 files. Using env GZIP=-9 tar cvzf kernel.tar.gz /opt/backup_test/linux produced a 2.8GB file. Again, using "best" compression with tar cf - /opt/backup_test/linux | xz -9e -T4 -c - > kernel.tar.bz produces a 2.6GB file, so there's probably big room for deduplication in the source files, even without running multiple consecutive backups on different points in time of the git repo.

backup multiple git repo versions to local repositories

Numbers:

Operation	bupstash 0.11.1	borg 1.2.2	borg_beta 2.0.0b2	kopia 0.12.0	restic 0.14.0	duplicacy 2.7.2
backup 1st run	9	41	55	10	23	32
backup 2nd run	11	22	25	4	8	13
backup 3rd run	7	28	39	7	17	23
backup 4th run	5	20	29	6	13	16
restore	4	16	17	5	9	11
size 1st run	213268	257300	265748	259780	260520	360200
size 2nd run	375776	338760	348248	341088	343060	480600
size 3rd run	538836	527732	543432	529812	531892	722176
size 4th run	655836	660812	680092	666408	668404	894984

Remarks:

• kopia was the best allround performer on local backups when it comes to speed, but is quite CPU intensive.
• bupstash was the most space efficient tool and is not CPU hungry.
• For the next instance, I'll need to post CPU / Memory / Disk IO usage graphs from my Prometheus instance.

backup multiple git repo versions to remote repositories

• Remote repositories are SSH (+ binary) for bupstash and burp.
• Remote repository is SFTP for duplicacy.
• Remote repository is HTTPS for kopia (kopia server with 2048 bit RSA certificate)
• Remote repository is HTTPS for restic (rest-server 0.11.0 with 2048 bit RSA certificate)

Numbers:

Operation	bupstash 0.11.1	borg 1.2.2	borg_beta 2.0.0b2	kopia 0.12.0	restic 0.14.0	duplicacy 2.7.2
backup 1st run	10	47	67	72	24	32
backup 2nd run	12	25	30	32	10	15
backup 3rd run	9	36	47	54	19	23
backup 4th run	7	31	50	46	21	23
restore	170	244	243	258	28	940
size 1st run	213240	257288	265716	255852	260608	360224
size 2nd run	375720	338720	348260	336440	342848	480856
size 3rd run	538780	527620	543204	522512	531820	722448
size 4th run	655780	660708	679868	657196	668436	895248

Remarks:

• With restic's recent release 0.14.0, the remote speeds using rest-server increased dramatically and are onpar with local backup results.
• All other programs take about 5-10x more time to restore than the initial backup, except for duplicacy, which has a 30x factor which is really bad
• Since last benchmark series, kopia 0.2.0 was released which resolves the remote bottleneck
• I finally switchted from ZFS to XFS remote filesystem so we have comparable file sizes between local and remote backups
• Noticing bad restore results, I've tried to tweak the SSH server:
  • The best cipher algorithm on my repository server was chacha-poly1305 (found with https://gist.github.com/joeharr4/c7599c52f9fad9e53f62e9c8ae690e6b)
  • Compression disabled
  • X11 Forwarding disabled (was already disabled)
  • The above settings were applied to sshd, so even duplicacy gets to use them, since I didn't find a way to configure those settings for duplicacy

backup private qemu disk images to remote repositories

Source data are 8 qemu qcow2 files, and 7 virtual machines description JSON files for a total of 366GB. Remote repositories are configured as above, except that I used ZFS as a backing filesystem.

Numbers:

Operation	bupstash 0.11.1	borg 1.2.2	borg_beta 2.0.0b2	kopia 0.12.0	restic 0.14.0	duplicacy 2.7.2
initial backup	4699	7044	6692	12125	8848	5889
initial size	121167779	123111836	122673523	139953808	116151424	173809600

Remarks:

As I did the backup benchmarks, I computed the average size of the files in each repository using

find /path/to/repository -type f -printf '%s\n' | awk '{s+=$0}
  END {printf "Count: %u\nAverage size: %.2f\n", NR, s/NR}'

Results for the linux kernel sources backups:

Software	Source	bupstash 0.11.1	borg 1.2.2	borg_beta 2.0.0b2	kopia 0.12	restic 0.14.0	duplicacy 2.7.2
File count	61417	2727	12	11	23	14	89
Avg file size (kb)	62	42	12292	13839	6477	10629	2079

I also computed the average file sizes in each repository for my private qemu images which I backup with all the tools using backup-bench.

Results for the qemu images backups:

Software	Source	bupstash 0.11.1	borg 1.2.2	borg_beta 2.0.0b2	kopia 0.12	restic 0.14.0	duplicacy 2.7.2
File count	15	136654	239	267	6337	66000	41322
Avg file size (kb)	26177031	850	468088	469933	22030	17344875	3838

Interesting enough, bupstash is the only software that produces sub megabyte chunks. Of the above 136654 files, only 39443 files weight more than 1MB. The qemu disk images are backed up to a ZFS filesystem with recordsize=1M. In order to measure the size difference, I created a ZFS filesystem with a 128k recordsize, and copied the bupstash repo to that filesystem. This resulted in bupstash repo size being roughly 13% smaller (137364728kb to 121167779kb). Since bupstash uses smaller chunk file sizes, I will continue using the 128k recordsize for the ZFS bupstash repository.

Footnotes

• Getting restic SFTP to work with a different SSH port made me roam restic forums and try various setups. Didn't succeed in getting RESTIC_REPOSITORY variable to work with that configuration.
• duplicacy wasn't as easy to script as the other tools, since it modifies the source directory (by adding .duplicacy folder) so I had to exclude that one from all the other backup tools.
• The necessity for duplicacy to cd into the directory to backup/restore doesn't feel natural to me.

EARLIER RESULTS

• 2022-09-06
• 2022-08-19

Links

As of 6 September 2022, I've posted an issue to every backup program's git asking if they could review this benchmark repo:

• bupstash: andrewchambers/bupstash#335
• restic: restic/restic#3917
• borg: borgbackup/borg#7007
• duplicacy: gilbertchen/duplicacy#635
• kopia: kopia/kopia#2375