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Performance #1
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Agree |
Is xdelta3 not threaded at all? That's where I see the bottleneck as well. I have VMs that are 200+GB and can do full backups very quickly, but a differential takes nearly all day because it's stuck in xdelta3 maxing out a single CPU core and not spreading the work out. |
it's not a multithread problem but a "network problem", really it's vzdump the big problem, when you'r backup start, it use your cifs/smb to read the old backup and doing a double write in same time : the vm snapshot in a dat/tmp file to compare with old backup and the delta vcdiff file... |
I have to disagree. I can run the same differential backups of large VMs on local storage (storage that can handle over 1GB/s of throughput) and the differential backup runs at about 4MB/s, checking CPU usage you can see xdelta3 running on only 1 core, for hours (18 hours for a 200GB VM specifically). It appears to be xdelta3 very poorly threaded. I've also found multiple other support threads where xdelta3 has been used in commercial products and they suffer the same issue. If you have a server with many slower cores (such as my Xeon E5-2650L based server), these differential backups are near useless for any large source VMs which is exactly where you need it to perform well. |
You say in local storage, but the problem is when using CIFS/SMB storage, it read the old backup from CIFS/SMB + it write the actual snapshot in a dat/tmp to the CIFS/SMB and then compare the old backup and the actual snapshot to write the vcdiff file... (double write CIFS/SMB + READ CIFS/SMB) ... it's a design problem that comes from vzdump in addition to the ayufan patch (which is not reactive at all) I agree with local storage, no problem... |
Hi |
Hi, |
Hi there! I have the same issue here too! The file is, indeed, reduced but slow down all vzdump process... How can we do something to improve this? |
Hi all, here having the same problem when differential backup is happening I'm using the patch for 5.4-5. normal backups are working at normal speed and differential backups speed drops drastically. All backups goes to same NFS storage. |
I did a few test on 5GB .vma files. If you add |
Perhaps we shoud compile more new xdelta3 version...
The one in github is bit older, 3.0.6 I thing...
There's a new version here:
https://github.com/jmacd/xdelta
Which I thing is 3.1 or something
And here too:
http://xdelta.org/
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Gilberto Nunes Ferreira
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Em sex, 30 de ago de 2019 às 20:20, Marcin <[email protected]>
escreveu:
I did a few test on 5GB .vma files. If you add -3 -B 2147483648 options
to xdelta3 you should get noticeably smaller diff copies. Disadvantage is
more memory consumption.
About speed. xdelta3 is single threaded, it uses gzip which is also single
threaded. If you find way to change gzip to pigz you backup should finish a
little faster.
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xdelta3 3.0.11 exists but is not downloaded by the patch installer. |
Have the same performance issue here, really small machine takes ways to long for a differential backup. Already running xdelta3 3.0.11, on backup routine it only takes one cpu core. Backup target is a cifs storage service (storage box from hetzner.com), full backups just takes 1 or 2 minutes and working properly. I like the differential solution, but with that bad performance I can't let it run on my other proxmox servers with larger vms. Is there any advice how to optimize it? Backup log:
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My guess is that if you want multi-core, you need to use LZMA and a multi-core compiled version of LZMA. |
Thanks for the answer @KlugFR, is there any docs how this can be done? |
Hello, |
Nothing new about how to resolve the issue? |
@MyTheValentinus @ScIT-Raphael Maybe try it with the recently released |
Hello,
I use zstd on this server. Maybe problem with zstd ?
Recently dist upgrade this proxmox (15 days ago)
Thanks
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On 2 Jun 2020, at 15:40, Kamil Trzciński ***@***.***> wrote:
@MyTheValentinus @ScIT-Raphael Maybe try it with the recently released zstd?
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Standard backup zstd mode snapshots: 110-130 mb/s |
Completely the same situation. In this current state, it's unusable. |
Same here, latest verison, still slow as hell :(. |
Hmm. Is the |
When i look the cpu usage, no core are 100%, i'm not sure that is linked to the single thread of xdelta. Before, other old version work fine in single core. |
Testing with edited /etc/vzdump.conf After this, I can see 28 cores in use out of 56. Before it was just 1. Backup still in process at the moment. Will keep you informed. |
@JoeApo108 Do you already have some feedback? Went the backup trough properly and fast? |
No, it didn't help at all...still slow. Ok, it might have smth to do with the source window size (-B switch). When I tested it with LXC of the tiny size than the full backup took (1.4GiB, 29MiB/s, archive size 410MB) and diff backup (1.4GiB, 23MiB/s, archive size 700kB) The huge LXC full backup took (320GiB, 52MiB/s, archive size 160GB) and diff ( ???? still in process) |
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Hello, |
We're having the same problem, using Proxmox v6.2-4 and the latest xdelta3. ZSTD full backup is quick, differential against it takes hours and hours until it basically stalls. Any solutions? |
Also would move to have a solution here, currently we just had to remove it again and switch back to normal backup. It's not usefull when a diff backup takes much longer than a full... |
I will do some regression testing to see why :)
…On Thu, 18 Jun 2020 at 08:07, Raphael Schneeberger ***@***.***> wrote:
Also would move to have a solution here, currently we just had to remove
it again and switch back to normal backup. It's not usefull when a diff
backup takes much longer than a full...
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I run some testing |
@ayufan Ok nice to hear that your have same issue. We waiting the fix thanks |
https://pbs.proxmox.com/wiki/index.php/Main_Page does dedup and compression. I think this solution from ayfan (thank you Kamil) will become deprecated. |
1.3 Main Features |
Would it make ayfan's solution deprecated though? I would need another server to be running just for backups? |
Both yes
…On Sun, 23 Aug 2020 at 22:52, ogghi ***@***.***> wrote:
Would it make ayfan's solution deprecated though? I would need another
server to be running just for backups?
I like the integrated solution.
(I found this thread because I was looking into the performance issues)
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Ayufan's solution is not integrated though, it's a modification that had a serious performance problem. PBS can be run in a container (I have it running in a Debian container) OR in a VM OR on bare metal. Any of those can be run anywhere you want. PBS is more flexible and more performant. |
Yes, additionally it is build differently not having the same performance
deficiency. Xdelta does not work well and being super performance. The best
way here is to work on blocks and compare blocks of fixed size. This gives
very predictable performance or just use copy on write.
…On Sun, 23 Aug 2020 at 23:41, sienar1 ***@***.***> wrote:
Would it make ayfan's solution deprecated though? I would need another
server to be running just for backups?
I like the integrated solution.
(I found this thread because I was looking into the performance issues)
Ayufan's solution is not integrated though, it's a modification that had a
serious performance problem. PBS can be run in a container (I have it
running in a Debian container) OR in a VM OR on bare metal. Any of those
can be run anywhere you want. PBS is more flexible and more performant.
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All right, will try PBS then on Openmediavault 👍 |
Can we do something about the performance?
Currently we use a CIFS/SMB volume via a 1Gbit/s interface.
A full backup for a medium sized VM needs about 2mins whereas it needs about 30mins to finish using xdelta3.
INFO: status: 70% (15040643072/21474836480), sparse 25% (5543481344), duration 1478, read/write 6/5 MB/s
As xdelta3 is only able to use one thread combined with a medium compression this is probably the bottleneck.
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