Skip to main content

CPANEL-43121 - File downloads from cPanel's File Manager are weirdly slow

spaceman
For reasons unknown, downloading files from cPanel's File Manager is weirdly slow, or highly variable in download speed, like they're being throttled. I've proved this across a number of servers, running different OS's and cPanel versions, and also with a 3rd party systems administrator. To test this for yourself, upload a large file (suggest > 500Mb) to a public_html folder, and test by downloading this file directly from the website, e.g.

Comments

24 comments

Date Votes
  • cPRex Jurassic Moderator
    Hey there! cPanel doesn't impose any type of ratelimiting on the system in any area, so it's definitely odd that you're seeing this. Unfortunately I don't have a good explanation. They do use different protocols, so I'm not surprised it's different, but it shouldn't be vastly different. How different were the speeds you were seeing?
    0
  • spaceman
    0
  • cPRex Jurassic Moderator
    What if you try with a smaller file, such as something in the 50M range? Do you see the same difference?
    0
  • spaceman
    Same issue, regardless of file size being downloaded. fyi: I created a full cPanel backup of an account today, size: 160Mb. Downloading it from the web interface took about 5 minutes Via ftp took 19 seconds. Advice from cPanel support is to disable "net.ipv4.tcp_tw_reuse" -
    0
  • cPRex Jurassic Moderator
    I don't think that sysctl change would be related at all. My thoughts on this are that the cPanel interface uses a customized PHP system to deliver the content. As in, you can completely kill Apache and PHP on the server, and the cPanel and WHM interfaces still continue to function. It wouldn't surprise me at all if your system is hitting the cPanel memory limit, or that we read the files much more slowly to conserve RAM. This would be especially apparent with larger files such as the ones you're working with, but with more "normal" files that are a few megs or less, users will likely not notice. You could try increasing the RAM allocated to cPanel in WHM >> Tweak Settings under the PHP section and see if that offers an improvement.
    0
  • spaceman
    Sincerely thanks for that. The VPS has plenty of spare resources: - RAM 32Gb, rarely uses more than 16Gb - 8 x vCPU, rarely uses more than 50% - Disk space, 525Gb used out of 700Gb Load averages are typically 2-3. Max cPanel process memory has been increased in Tweak Settings from 4096 (default) to 8192. Max cPanel/WHM/Webmail service handlers has been increased in Tweak Settings from 200 (default) to 1,000. Still no improvement :-/ The truth (solution) is out there - somewhere!
    0
  • cPRex Jurassic Moderator
    I don't think there is a solution to this one - I think we just secretly ratelimit large downloads to limit cPanel's RAM usage at the expense of speed.
    0
  • spaceman
    Bizarre!
    0
  • cPRex Jurassic Moderator
    I've created case CPANEL-43121 for our team to look into this. As people start and use File Manager more than FTP, this is something I would hope we can resolve. I'll let you know if/when I hear an update!
    0
  • spaceman
    Thanks for this:
    0
  • spaceman
    I wish we could find a resolution to issue issue! I've just downloaded a backup from JetBackup 5 (same protocol as cPanel backups, no doubt), and it's taken about 30 mins to download a small 365Mb file. In all other respects, this is from a high performing, high specification server running the latest OS,cPanel, and at a time when there's low load on the server.
    0
  • spaceman
    Is it possible to escalate this issue? It's seriously negatively affecting the satisfaction of our customers when they're attempting to download backups. Hopefully the reason is just one thing. It just requires some focused diagnostic/troubleshooting effort by a suitably skilled tech.
    0
  • cPRex Jurassic Moderator
    @spaceman - we already know the reason, so no additional diagnosing or troubleshooting is necessary. It's just up to a development team to take on the work to fix the issue. I've been hearing off and on for *years* that we'll be getting rid of FTP. Well, it hasn't happened yet, but I do think it will someday. So I think this case will definitely get fixed. What I can't say is when the case will get resolved, as I don't see that a specific internal team has picked it up just yet.
    0
  • spaceman
    OK, great to know that you know the reason. I sincerely hope it's not a complex or controversial fix. Downloading (large) backup files at a typical speed of <10 kb/s is NOT fun! Sure, on occasions during a download the transfer speed temporarily bounces up to 2-10Mb/s (where it should be all the time!), but then for no apparent reason falls back to <10kb/s. Aaaargh!!!
    0
  • spaceman
    Call me old-fashioned, but IMHO this is a high-impact issue, with probably/hopefully a relatively simple fix, and therefore deserves to be towards the top of the queue.
    0
  • spaceman

    This is still going on, of course.

    Trying to download a 7.5Gb Jetbackup file.

    Download speeds vary up & down, up & down.

    One moment it's downloading at 10 MB/s with an ETA of 10 mins.

    Then the download speed falls off a cliff down to 4 KB/s with an ETA of 14 days!

    This issue was flagged 11 years ago: https://support.cpanel.net/hc/en-us/community/posts/19621737493015-Slow-Download-Speed-when-downloading-backups

    0
  • spaceman

    And just to rub salt in the wounds, my attempt to download the 7.5Gb compressed backup is repeatedly failing and restarting. Twice (and counting).

    I got up to about 2.5Gb of 7.5Gb downloaded, then it restarted, and is now up to 0.5 GB downloaded.

    Sigh.

     

    0
  • cPRex Jurassic Moderator

    Well that's fun.

    The bad news, as that I don't see any action on this case just yet.  There are some thoughts and additional details added, but no actual work.

    I brought this up with the dev team just now so hopefully this will see some action soon.  I'll be sure to post an update here if I hear anything!

    0
  • spaceman

    Naturally if you'd like a guinea pig to work with for some in-depth analysis/testing, I'm available.

    0
  • cPRex Jurassic Moderator

    I would *think* this is easy enough to reproduce, but I'll let you know if we need anything!

    0
  • spaceman

    fyi I gave up trying to download the 7.5Gb file via https from the WHM > Jetbackup list of backups. It was failing repeatedly (about 10 times?) after, say, 2-4Gb had been downloaded each time.

    So now I've just sftp'd to the server using Filezilla, navigated to the downloads directory (/usr/local/jetapps/usr/jetbackup5/downloads) and have successfully downloaded the file, first time, at a rock solid speed of 9.4 MiB/s. It took 13 mins.

    0
  • rolinger
    • Edited

    I am experiencing the same thing.  Downloading a 1.7Gb file with my 500Mb home link is absolutely creeping.  its half downloaded now with 1 hour to go.  What is causing this to be throttled?

    On another 2Gb file I was able to upload in about 20 seconds.

    So its not a server or bandwidth issue...and if FTP can download the file in 30 seconds then so should the File Manager download - but obviously something in cpanel is impeding it.

    Oddly though, if you go into cpanel backup wizard, it can zip and download the files in normal time - so its something specific to cPanel File Manager.

    0
  • rolinger

    and FYI to cPanel - you might want to prioritize this.  The fact that this was reported 11 years ago (as spaceman mentioned above) means its a pretty bad look for cPanel to have known about this for SOOO long and have done nothing about it.

    0
  • cPRex Jurassic Moderator

    @... - I've added your feedback to the case.

    0

Please sign in to leave a comment.

Didn't find what you were looking for?

New post