Slow Backup to 8Tb Seagate drive, killing the NAS performance

Currently reading
Slow Backup to 8Tb Seagate drive, killing the NAS performance

Operating system
  1. macOS
Mobile operating system
  1. iOS
I use an 8Tb external drive, this Seagate backup drive, which is used to back up 'critical data' from the NAS. This is plugged directly into the USB port on the back of the NAS. Yesterday I got a message from the NAS saying it was full. I therefore reformatted it (EXT4) and created a new backup job.

The backup job was triggered last night at 23:00 hours, so far it's only 26% completed, the transfer rate is varying between 10-18 MB/sec. It's now 13:46.

Apart from it being painfully slow on the transfer it's slowing the NAS down so much that users can hardly access the forum I host on it. It's never been fast but now it takes 15-20 pages to load a page.

Any ideas guys?

Screenshot 2022-10-17 at 13.44.56.jpg
I'm fairly sure the hard disk inside the Seagate Backup Plus Hub would be SMR, which won't have great write performance.

I would also suggest trying a different USB cable, as I've often found cheap and/or defective supplied cables with external drives that hurt performance.

If you can return the unit and exchange for the 10TB version, this will be a CMR drive.
The drive was bought back in 2017, so a bit late to send it back now I guess :) As it is a backup drive it does not really need that performance (for PC etc), I'd not be bothered here if it was not slowing the NAS up so much.

The USB cable is an Amazon 'basic' cable. So yeah time to swap that out with a higher spec'ed cable I guess.
Maybe, it is still working well enough. It's in its original enclosure, who knows...... Oh well it's got a lot of data to get through. I just wish there was a way to give less resource to it and more to the Web Station....
Last edited:
To try and give the Web Station a bit of a boost I've installed PHP 8.0 and switched to using that instead of PHP 7.4.

Alas I can't remove PHP 7.4 as Synology have tied it to phpMyAdmin and it looks like I can't easily stop it running. So I may swap back to 7.4 and uninstall 8 again.
-- post merged: --

Well the gods know why but it seems I've fixed the performance issue with respect to Web Station. I've stopped Homebridge, stopped Docker, restarted Docker then Homebridge. Forum pages are now loading in less then a second and SQL (View New Content) queries in around 3 seconds.
It slowed down again alas, not as bad as before but........ So i've stopped Homebridge and Docker which has helped. Installed Packages are:
Screenshot 2022-10-17 at 18.54.08.jpg
Screenshot 2022-10-17 at 18.54.54.jpg
Last edited:
Hmm I just noticed this was not turned on. I hope it makes a difference:
Screenshot 2022-10-17 at 19.53.54.jpg

The running processes are:
Screenshot 2022-10-17 at 20.09.41.jpg

Screenshot 2022-10-17 at 20.22.55.jpg
Last edited:
Hmm right.. Okay so it looks like it may be worthwhile to load PHP 8.0, and switch over to using that even though I'll be unable to remove PHP 7.4 and both will be active on the NAS.
Changed PHP and IO wait is now sitting at 37 - 49%, so that has helped. I guess we'll have to see what it looks like after the backup eventually completes and I reboot the NAS.
Well from the images, it looks like the NAS side of things is working and the volume itself (not the USB drive) is having a lot of IOWait % Now while that might be fine if there are a lot of transfers and smaller files (also a large number of files), the speed transfer is not bad at all.

Guessing it's not just large files that are being transferred here. If this did work much faster before, it could be also that some other service or app is utilizing the volume and its IOPS, leaving the actual transfer slower and the whole volume a bit more utilized.

The process screen from yesterday does not show any other major process using the resources that much. considering docker is stopped the only thing that might use the volume all the time is SS or Plex. Again, not sure that multiple video streams would cause a lot of volume action, and Plex as well (unless you have multiple transcode streams kicking in at the same time).

Turning more services off will free up more resources for sure, but again, this might actually be that the backup process is doing the most "damage" to the rest of the services on the same pool due to a large number of files that needed backing up.

Until it's done, and start making incremental backups it will be difficult to pinpoint the root cause without further testing.
Last edited:
Yep, agreed..... There are a lot of films and TV shows to backup so a lot of large files... I've already disabled:
  • Docker / Homebridge
  • Cloud Sync
  • Plex
SS is not running, so yeah I'm thinking the backup process is causing the damage we'll have what things look like when it eventually completes.
-- post merged: --

I've now turned off the 'Antivirus Essential' package and backup thoughput had gone up by about 8% plus the forum is running faster. I may leave it off in the future as I've never hen that impressed with it....
I've also stopped the Log Center

Hmm.... Replication Service - can this be uninstalled? Wondering as I'm not replicating across devices at all?
I've also stopped the Log Center

Hmm.... Replication Service - can this be uninstalled? Wondering as I'm not replicating across devices at all?
No you can't as it is a support element for Snapshot Replication tool, but also for some other elements as well. So even if you are not running SR it will not be possible to stop/remove it without stopping/removing another package (similar to the PHP situation that you had).

Create an account or login to comment

You must be a member in order to leave a comment

Create account

Create an account on our community. It's easy!

Log in

Already have an account? Log in here.

Similar threads

For mixed size files, this speed seems ok to me. Many small files bring back read/write speed...
Yes. I just changed the timing of the integrity check, giving it enough time to complete before backup...
Unfortunately, HB does not support QC. It's either, a public IP, DDNS, or LAN IP.
Backup software cannot accurately predetermine what its final backup size is going to be. You need to...
Well I'm glad it was just an unplug issue this time.
  • Question
That will work with 4.1 version. Looks like user feedback has been implemented.
Hello eveyrone, Out of nowhere, now getting ""server data backup task on <server name> failed." Digging...

Welcome to! is an unofficial Synology forum for NAS owners and enthusiasts.

Registration is free, easy and fast!

Trending threads