Backups failing. How much storage overhead is needed to make a VM backup?

Tech_Geek97

New Member
Sep 3, 2024
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I have moved this thread from the Proxmox Backup forum as the issue does not involve a Proxmox Backup server.

I am attempting to back up a VM with an 18TB disk allocated of which 17.6TiB is used to a 20TB external HDD. In the local-lvm "vm-201-disk-1" is listed as having a size of 19.33TB Unfortunately the backup has now failed twice with the same error "zstd: error 70 : Write error : cannot write block : File too large" followed by the error "ERROR: vma_queue_write: write error - Broken pipe". I have posted the full log below. I am gathering that this error is due to a lack of space but due to the time this backup takes I have not been able to see the external disk usage at the moment the backups fails, but the disk was only shown to be 85% full (of 19.93TB) at the time the backup was 93% complete. I believe I need to delete some data to make the backup fit but I can not seem to find any documentation that indicates a ratio or formula to calculate how much larger a backup volume needs to be than the size of the backup I am trying to take as I would think that over 2TiB would be enough space for a compression temp directory. Does anyone have experience with this issue, know where I can find more verbose logs, or know of some piece of documentation I am missing? Any insight or suggestions would be very much appreciated.


Code:
INFO: starting new backup job: vzdump 201 --compress zstd --notification-mode auto --remove 0 --node proxmox1 --mode stop --storage [REMOVED]Backup --notes-template '{{guestname}}'
INFO: Starting Backup of VM 201 (qemu)
INFO: Backup started at 2024-08-28 18:26:42
INFO: status = running
INFO: backup mode: stop
INFO: ionice priority: 7
INFO: VM Name: [REMOVED]
INFO: include disk 'scsi0' 'local-lvm:vm-201-disk-1' 18000G
INFO: include disk 'efidisk0' 'local-lvm:vm-201-disk-0' 4M
INFO: stopping virtual guest
INFO: snapshots found (not included into backup)
INFO: creating vzdump archive '/media/usb-drive/dump/vzdump-qemu-201-2024_08_28-18_26_42.vma.zst'
INFO: starting kvm to execute backup task
INFO: started backup task '698251e8-5f25-4e57-b424-92251a0bf521'
INFO: resuming VM again after 53 seconds
INFO:   0% (1.8 GiB of 17.6 TiB) in 3s, read: 601.8 MiB/s, write: 195.4 MiB/s
INFO:   1% (180.0 GiB of 17.6 TiB) in 1h 16m 6s, read: 40.0 MiB/s, write: 39.3 MiB/s
INFO:   2% (360.0 GiB of 17.6 TiB) in 2h 35m 52s, read: 38.5 MiB/s, write: 37.9 MiB/s
INFO:   3% (540.0 GiB of 17.6 TiB) in 3h 56m 25s, read: 38.1 MiB/s, write: 37.5 MiB/s
INFO:   4% (720.0 GiB of 17.6 TiB) in 5h 15m 45s, read: 38.7 MiB/s, write: 37.7 MiB/s
INFO:   5% (900.0 GiB of 17.6 TiB) in 6h 35m 48s, read: 38.4 MiB/s, write: 37.7 MiB/s
INFO:   6% (1.1 TiB of 17.6 TiB) in 7h 56m 39s, read: 38.0 MiB/s, write: 37.4 MiB/s
INFO:   7% (1.2 TiB of 17.6 TiB) in 9h 16m 18s, read: 38.6 MiB/s, write: 38.0 MiB/s
INFO:   8% (1.4 TiB of 17.6 TiB) in 10h 38m 4s, read: 37.6 MiB/s, write: 37.0 MiB/s
INFO:   9% (1.6 TiB of 17.6 TiB) in 11h 59m 17s, read: 37.8 MiB/s, write: 37.2 MiB/s
INFO:  10% (1.8 TiB of 17.6 TiB) in 13h 18m 49s, read: 38.6 MiB/s, write: 37.4 MiB/s
INFO:  11% (1.9 TiB of 17.6 TiB) in 14h 38m 30s, read: 38.5 MiB/s, write: 37.5 MiB/s
INFO:  12% (2.1 TiB of 17.6 TiB) in 15h 55m 51s, read: 39.7 MiB/s, write: 37.7 MiB/s
INFO:  13% (2.3 TiB of 17.6 TiB) in 17h 16m 10s, read: 38.2 MiB/s, write: 37.4 MiB/s
INFO:  14% (2.5 TiB of 17.6 TiB) in 18h 35m 19s, read: 38.8 MiB/s, write: 37.3 MiB/s
INFO:  15% (2.6 TiB of 17.6 TiB) in 19h 54m 10s, read: 39.0 MiB/s, write: 37.6 MiB/s
INFO:  16% (2.8 TiB of 17.6 TiB) in 21h 14m 38s, read: 38.2 MiB/s, write: 37.5 MiB/s
INFO:  17% (3.0 TiB of 17.6 TiB) in 22h 33m 44s, read: 38.8 MiB/s, write: 37.6 MiB/s
INFO:  18% (3.2 TiB of 17.6 TiB) in 23h 51m 33s, read: 39.5 MiB/s, write: 37.2 MiB/s
INFO:  19% (3.3 TiB of 17.6 TiB) in 1d 1h 10m 15s, read: 39.0 MiB/s, write: 37.3 MiB/s
INFO:  20% (3.5 TiB of 17.6 TiB) in 1d 2h 30m 22s, read: 38.3 MiB/s, write: 37.3 MiB/s
INFO:  21% (3.7 TiB of 17.6 TiB) in 1d 3h 46m 39s, read: 40.3 MiB/s, write: 37.4 MiB/s
INFO:  22% (3.9 TiB of 17.6 TiB) in 1d 5h 3m 23s, read: 40.0 MiB/s, write: 37.6 MiB/s
INFO:  23% (4.0 TiB of 17.6 TiB) in 1d 6h 19m 43s, read: 40.2 MiB/s, write: 37.9 MiB/s
INFO:  24% (4.2 TiB of 17.6 TiB) in 1d 7h 36m 40s, read: 39.9 MiB/s, write: 37.6 MiB/s
INFO:  25% (4.4 TiB of 17.6 TiB) in 1d 8h 56m 58s, read: 38.3 MiB/s, write: 37.0 MiB/s
INFO:  26% (4.6 TiB of 17.6 TiB) in 1d 10h 11m 6s, read: 41.4 MiB/s, write: 36.9 MiB/s
INFO:  27% (4.7 TiB of 17.6 TiB) in 1d 11h 30m 26s, read: 38.7 MiB/s, write: 36.9 MiB/s
INFO:  28% (4.9 TiB of 17.6 TiB) in 1d 12h 50m 41s, read: 38.3 MiB/s, write: 36.7 MiB/s
INFO:  29% (5.1 TiB of 17.6 TiB) in 1d 14h 7m 38s, read: 39.9 MiB/s, write: 37.7 MiB/s
INFO:  30% (5.3 TiB of 17.6 TiB) in 1d 15h 26m 10s, read: 39.1 MiB/s, write: 38.1 MiB/s
INFO:  31% (5.4 TiB of 17.6 TiB) in 1d 16h 41m 28s, read: 40.8 MiB/s, write: 38.3 MiB/s
INFO:  32% (5.6 TiB of 17.6 TiB) in 1d 17h 59m 18s, read: 39.5 MiB/s, write: 37.6 MiB/s
INFO:  33% (5.8 TiB of 17.6 TiB) in 1d 19h 15m 55s, read: 40.1 MiB/s, write: 37.8 MiB/s
INFO:  34% (6.0 TiB of 17.6 TiB) in 1d 20h 31m 54s, read: 40.4 MiB/s, write: 38.1 MiB/s
INFO:  35% (6.2 TiB of 17.6 TiB) in 1d 21h 51m 22s, read: 38.7 MiB/s, write: 37.4 MiB/s
INFO:  36% (6.3 TiB of 17.6 TiB) in 1d 23h 8m 8s, read: 40.0 MiB/s, write: 37.9 MiB/s
INFO:  37% (6.5 TiB of 17.6 TiB) in 2d 26m 17s, read: 39.3 MiB/s, write: 37.4 MiB/s
INFO:  38% (6.7 TiB of 17.6 TiB) in 2d 1h 33m 2s, read: 46.0 MiB/s, write: 37.4 MiB/s
INFO:  39% (6.9 TiB of 17.6 TiB) in 2d 2h 52m 42s, read: 38.6 MiB/s, write: 36.9 MiB/s
INFO:  40% (7.0 TiB of 17.6 TiB) in 2d 4h 11m 47s, read: 38.8 MiB/s, write: 36.9 MiB/s
INFO:  41% (7.2 TiB of 17.6 TiB) in 2d 5h 32m 42s, read: 38.0 MiB/s, write: 36.9 MiB/s
INFO:  42% (7.4 TiB of 17.6 TiB) in 2d 6h 54m 25s, read: 37.6 MiB/s, write: 36.7 MiB/s
INFO:  43% (7.6 TiB of 17.6 TiB) in 2d 8h 15m 23s, read: 37.9 MiB/s, write: 37.2 MiB/s
INFO:  44% (7.7 TiB of 17.6 TiB) in 2d 9h 35m 51s, read: 38.2 MiB/s, write: 37.0 MiB/s
INFO:  45% (7.9 TiB of 17.6 TiB) in 2d 10h 57m 44s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  46% (8.1 TiB of 17.6 TiB) in 2d 12h 19m 46s, read: 37.4 MiB/s, write: 36.8 MiB/s
INFO:  47% (8.3 TiB of 17.6 TiB) in 2d 13h 41m 46s, read: 37.5 MiB/s, write: 36.7 MiB/s
INFO:  48% (8.4 TiB of 17.6 TiB) in 2d 15h 59s, read: 38.8 MiB/s, write: 36.7 MiB/s
INFO:  49% (8.6 TiB of 17.6 TiB) in 2d 16h 20m 3s, read: 38.9 MiB/s, write: 36.8 MiB/s
INFO:  50% (8.8 TiB of 17.6 TiB) in 2d 17h 41m 51s, read: 37.6 MiB/s, write: 36.8 MiB/s
INFO:  51% (9.0 TiB of 17.6 TiB) in 2d 19h 42s, read: 39.0 MiB/s, write: 36.8 MiB/s
INFO:  52% (9.1 TiB of 17.6 TiB) in 2d 20h 18m 22s, read: 39.6 MiB/s, write: 37.2 MiB/s
INFO:  53% (9.3 TiB of 17.6 TiB) in 2d 21h 36m 53s, read: 39.1 MiB/s, write: 36.8 MiB/s
INFO:  54% (9.5 TiB of 17.6 TiB) in 2d 22h 55m 15s, read: 39.2 MiB/s, write: 36.9 MiB/s
INFO:  55% (9.7 TiB of 17.6 TiB) in 3d 14m 50s, read: 38.6 MiB/s, write: 36.9 MiB/s
INFO:  56% (9.8 TiB of 17.6 TiB) in 3d 1h 34m 27s, read: 38.6 MiB/s, write: 37.0 MiB/s
INFO:  57% (10.0 TiB of 17.6 TiB) in 3d 2h 56m 19s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  58% (10.2 TiB of 17.6 TiB) in 3d 4h 16m 56s, read: 38.1 MiB/s, write: 37.4 MiB/s
INFO:  59% (10.4 TiB of 17.6 TiB) in 3d 5h 36m 21s, read: 38.7 MiB/s, write: 38.0 MiB/s
INFO:  60% (10.5 TiB of 17.6 TiB) in 3d 6h 57m 36s, read: 37.8 MiB/s, write: 37.2 MiB/s
INFO:  61% (10.7 TiB of 17.6 TiB) in 3d 8h 19m 32s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  62% (10.9 TiB of 17.6 TiB) in 3d 9h 41m 30s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  63% (11.1 TiB of 17.6 TiB) in 3d 11h 3m 39s, read: 37.4 MiB/s, write: 36.7 MiB/s
INFO:  64% (11.3 TiB of 17.6 TiB) in 3d 12h 25m 29s, read: 37.5 MiB/s, write: 36.9 MiB/s
INFO:  65% (11.4 TiB of 17.6 TiB) in 3d 13h 47m 12s, read: 37.6 MiB/s, write: 36.9 MiB/s
INFO:  66% (11.6 TiB of 17.6 TiB) in 3d 15h 9m 16s, read: 37.4 MiB/s, write: 36.8 MiB/s
INFO:  67% (11.8 TiB of 17.6 TiB) in 3d 16h 28m 12s, read: 38.9 MiB/s, write: 38.2 MiB/s
INFO:  68% (12.0 TiB of 17.6 TiB) in 3d 17h 49m 51s, read: 37.6 MiB/s, write: 36.9 MiB/s
INFO:  69% (12.1 TiB of 17.6 TiB) in 3d 19h 9m 9s, read: 38.7 MiB/s, write: 36.7 MiB/s
INFO:  70% (12.3 TiB of 17.6 TiB) in 3d 20h 31m 30s, read: 37.3 MiB/s, write: 36.6 MiB/s
INFO:  71% (12.5 TiB of 17.6 TiB) in 3d 21h 53m 56s, read: 37.3 MiB/s, write: 36.6 MiB/s
INFO:  72% (12.7 TiB of 17.6 TiB) in 3d 23h 16m 21s, read: 37.3 MiB/s, write: 36.6 MiB/s
INFO:  73% (12.8 TiB of 17.6 TiB) in 4d 38m 32s, read: 37.4 MiB/s, write: 36.7 MiB/s
INFO:  74% (13.0 TiB of 17.6 TiB) in 4d 2h 36s, read: 37.4 MiB/s, write: 36.8 MiB/s
INFO:  75% (13.2 TiB of 17.6 TiB) in 4d 3h 22m 19s, read: 37.6 MiB/s, write: 36.9 MiB/s
INFO:  76% (13.4 TiB of 17.6 TiB) in 4d 4h 44m 35s, read: 37.3 MiB/s, write: 36.7 MiB/s
INFO:  77% (13.5 TiB of 17.6 TiB) in 4d 6h 6m 9s, read: 37.7 MiB/s, write: 37.0 MiB/s
INFO:  78% (13.7 TiB of 17.6 TiB) in 4d 7h 27m 11s, read: 37.9 MiB/s, write: 37.2 MiB/s
INFO:  79% (13.9 TiB of 17.6 TiB) in 4d 8h 49m 7s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  80% (14.1 TiB of 17.6 TiB) in 4d 10h 10m 56s, read: 37.5 MiB/s, write: 36.9 MiB/s
INFO:  81% (14.2 TiB of 17.6 TiB) in 4d 11h 32m 36s, read: 37.6 MiB/s, write: 36.9 MiB/s
INFO:  82% (14.4 TiB of 17.6 TiB) in 4d 12h 54m 33s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  83% (14.6 TiB of 17.6 TiB) in 4d 14h 16m 41s, read: 37.4 MiB/s, write: 36.7 MiB/s
INFO:  84% (14.8 TiB of 17.6 TiB) in 4d 15h 38m 41s, read: 37.5 MiB/s, write: 36.7 MiB/s
INFO:  85% (14.9 TiB of 17.6 TiB) in 4d 17h 37s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  86% (15.1 TiB of 17.6 TiB) in 4d 18h 22m 31s, read: 37.5 MiB/s, write: 36.8 MiB/s
INFO:  87% (15.3 TiB of 17.6 TiB) in 4d 19h 44m 39s, read: 37.4 MiB/s, write: 36.7 MiB/s
INFO:  88% (15.5 TiB of 17.6 TiB) in 4d 21h 5m 14s, read: 38.1 MiB/s, write: 37.4 MiB/s
INFO:  89% (15.6 TiB of 17.6 TiB) in 4d 22h 27m 1s, read: 37.6 MiB/s, write: 36.8 MiB/s
INFO:  90% (15.8 TiB of 17.6 TiB) in 4d 23h 45m 42s, read: 39.0 MiB/s, write: 37.1 MiB/s
INFO:  91% (16.0 TiB of 17.6 TiB) in 5d 1h 3m 24s, read: 39.6 MiB/s, write: 37.2 MiB/s
INFO:  92% (16.2 TiB of 17.6 TiB) in 5d 2h 21m 38s, read: 39.2 MiB/s, write: 36.9 MiB/s
INFO:  93% (16.3 TiB of 17.6 TiB) in 5d 3h 39m 30s, read: 39.5 MiB/s, write: 37.1 MiB/s
INFO:  94% (16.5 TiB of 17.6 TiB) in 5d 4h 55m 23s, read: 40.5 MiB/s, write: 37.2 MiB/s
INFO:  95% (16.7 TiB of 17.6 TiB) in 5d 5h 59m 34s, read: 47.9 MiB/s, write: 38.8 MiB/s
INFO:  96% (16.9 TiB of 17.6 TiB) in 5d 6h 31m 27s, read: 96.4 MiB/s, write: 42.8 MiB/s
INFO:  97% (17.1 TiB of 17.6 TiB) in 5d 7h 11m 38s, read: 76.4 MiB/s, write: 37.7 MiB/s
zstd: error 70 : Write error : cannot write block : File too large
INFO:  97% (17.1 TiB of 17.6 TiB) in 5d 7h 17m 48s, read: 40.9 MiB/s, write: 38.3 MiB/s
ERROR: vma_queue_write: write error - Broken pipe
INFO: aborting backup job
INFO: resuming VM again
ERROR: Backup of VM 201 failed - vma_queue_write: write error - Broken pipe
INFO: Failed at 2024-09-03 01:46:19
INFO: Backup job finished with errors
INFO: notified via target `mail-to-root`
TASK ERROR: job errors
 
Last edited:
When I search the Internet for the error message, I always find information that there is no more free disk space.
Have a look at the Proxmox Stats, there you can see very nicely how the consumption was at the backup time.

For example:

Screenshot_20240904_110058.png
 
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what filesystem is used on the backup storage? with which settings? the error would indicate the backup archive itself grows too large and runs into a file size limit..
 
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When I search the Internet for the error message, I always find information that there is no more free disk space.
Have a look at the Proxmox Stats, there you can see very nicely how the consumption was at the backup time.

For example:

View attachment 74212
Thanks for the tip on the time period drop down. It seems pretty clear that the disk does not become completely full before the backup fails.
1725451545517.png

what filesystem is used on the backup storage? with which settings? the error would indicate the backup archive itself grows too large and runs into a file size limit..
The drive is formatted ext4. I am reading that there is a 16TiB maximum file size with the default 4KiB block size size so this is likely the issue (not sure why it fails at 17TiB not 16TiB). Do you think it would be better to reformat with a larger block size, or to reformat with a different file system entirely? XFS perhaps?
 
Last edited:
since you seem to be using that disk only as backup target, either ext4 with a bigger block size (shouldn't affect VMA-based backups negatively), or an FS that supports bigger files out of the box (IIRC XFS for example does) should be fine.
 
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since you seem to be using that disk only as backup target, either ext4 with a bigger block size (shouldn't affect VMA-based backups negatively), or an FS that supports bigger files out of the box (IIRC XFS for example does) should be fine.
I have reformatted the disk as XFS and am starting a new backup task. I will update this thread with how it goes either way. I appreciate everyone's insight and input.
 
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