Windows client slowing down to a crawl

client
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I’m currently doing a LARGE backup of a Windows system (almost 19TB), it’s been going for about 1.5 day, 7TB in, and has been behaving as expected until now, performance being limited visibly either by network speed or disk I/O on either client and server.
But now for the last couple of hours transfer has been hovering steadily at about 4Mbit/s. Both CPU and disk are basically idle on both sides, no CPU use from the client, network is available and runs at full speed…

This doesn’t seem to be an issue with the server since I can power up another machine and it’ll do its incremental backup in the expected time, network’s good both in general and between the 2 machines, it seems the Windows client just doesn’t want to do work…

I’ve looked in the debug.log and the only thing I get is lines like

2022-07-08 15:12:12: WARNING: Parent of file with FRN 21110623254091828 (Name "004B0000000C183451B93F31") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:12:12: WARNING: Parent directory not found in MFT. Was probably deleted.
2022-07-08 15:12:12: WARNING: Parent of file with FRN 21110623254091828 (Name "004B0000000C183451B93F31") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:12:12: WARNING: Parent directory not found in MFT. Was probably deleted.
2022-07-08 15:12:32: WARNING: Parent of file with FRN 13229323906193474 (Name "002F0000000C184262BD519C") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:12:32: WARNING: Parent directory not found in MFT. Was probably deleted.
2022-07-08 15:12:32: WARNING: Parent of file with FRN 13229323906193474 (Name "002F0000000C184262BD519C") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:12:32: WARNING: Parent directory not found in MFT. Was probably deleted.
2022-07-08 15:16:02: WARNING: Parent of file with FRN 9007199255482825 (Name "00200000000B51C936B48DEB") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:16:02: WARNING: Parent directory not found in MFT. Was probably deleted.
2022-07-08 15:16:02: WARNING: Parent of file with FRN 9007199255482825 (Name "00200000000B51C936B48DEB") with FRN 281474976710685 not found. Searching via MFT as fallback.
2022-07-08 15:16:02: WARNING: Parent directory not found in MFT. Was probably deleted.

Frequency varies, but sometimes there are no new such errors for 15 minutes yet speed still doesn’t go back to normal so not sure it’s related. Maybe there’s a problem because the VSS was done so long ago (more than a day now)?

What would be the thing to do at this point? Obviously can’t wait for the full year the estimate gives, I could reboot but am afraid of issues on restart, how does transfer/deduplication work on a resumed full file backup? Having the 7TB transferred again would be a pain but not a real problem, but if the 7TB stays stored on the server along with the new data and deduplication only takes place at the end I would have a problem because the server would not have enough space to store everything until those 7TB got deduped…

Thanks

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I’d wait a bit first to see if it’s just variance… but resumed backups shouldn’t cause any problems.

Is it a laptop (i.e., can it go into a power saving mode where it throttles background transfers?)?

You can see what it does if you go to Activities → Live Log on the server.

On the client e.g. run procmon.exe and see what UrBackupClientBackend.exe does.

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Thanks for the reply.
This is a desktop, no power saving. Process Hacker simply showed barely any activity. Live log showed things coming, with the progress report of a given file every minute just going extremely slowly, couple of % each time of a file a few MB big…

It was still doing the same after about 7 hours, strangely constantly hovering between 3.5 and 4.5Mbit/s so I restarted both client and server, not much choice at that point. It runs as expected again now.

Backup seems to have resumed correctly indeed, it’s showing X of “only” 11.5TB and the live log showed things that have indeed been added/changed in the meantime at the beginning, and where it’s now in the folder hierarchy is basically just after where it got hung so I should be good.

Anyway thanks, somehow only found out about urbackup a few weeks ago from a forum post, and it’s exactly what I had been looking for all this time… Did a bunch of testing since and now shuffled hardware to build a server basically centered around it :slight_smile:

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Windows has lots of hidden power saving features, even for desktops and servers, that help manufacturers get the Energy Star certification. One sneaky place is in the network adapter settings where the connection is silently turned off when Windows thinks you’re not using it. (Windows is often wrong about that, so one product I support includes a special utility to disable that shutdown.)

The detailed Sleep settings may reveal more, even things that happen in the name of power saving without a full system Sleep event.

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Yeah in this case I was actively using the machine, while it was stuck I was perfectly able to send stuff at 1 gigabit to another service on the same server etc… really everything else on the machine was working normally.