Local rsync and cp is very slow compared to SMB

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    • Local rsync and cp is very slow compared to SMB

      Hello there!

      I am doing some testing of OMV before using it as my main NAS OS. The hardware is an ODROID HC1 with a 2.5" WD SATA drive.

      I am having a strange issue (at least it seems strange to me). I was testing the USB Backup plugin and the speeds were very underwhelming. Backing up a 5 GB share took roughly 15 minutes, equating a transfer rate of around 5 MB/s. I suspected that the problem might be related to the plugin itself, and therefore did some tests using plain rsync and cp to transfer files between the internal SATA drive and an attached USB thumb drive. The results are still disappointing:

      Display Spoiler
      sending incremental file list
      5,097,472 100% 98.57MB/s 0:00:00 (xfr#1, to-chk=223/224)
      6,557,696 100% 57.91MB/s 0:00:00 (xfr#2, to-chk=222/224)
      80,812,549 100% 92.08MB/s 0:00:00 (xfr#3, to-chk=221/224)
      5,696,000 100% 4.74MB/s 0:00:01 (xfr#4, to-chk=220/224)
      19,548,672 100% 16.09MB/s 0:00:01 (xfr#5, to-chk=219/224)
      5,396,992 100% 9.19MB/s 0:00:00 (xfr#6, to-chk=218/224)
      19,523,072 100% 3.34MB/s 0:00:05 (xfr#7, to-chk=217/224)
      6,629,376 100% 19.39MB/s 0:00:00 (xfr#8, to-chk=216/224)
      19,674,112 100% 6.56MB/s 0:00:02 (xfr#9, to-chk=215/224)
      5,747,200 100% 3.44MB/s 0:00:01 (xfr#10, to-chk=214/224)
      19,599,872 100% 5.16MB/s 0:00:03 (xfr#11, to-chk=213/224)
      4,806,144 100% 3.27MB/s 0:00:01 (xfr#12, to-chk=212/224)
      19,472,896 100% 4.84MB/s 0:00:03 (xfr#13, to-chk=211/224)
      4,546,560 100% 2.36MB/s 0:00:01 (xfr#14, to-chk=210/224)
      19,438,080 100% 6.89MB/s 0:00:02 (xfr#15, to-chk=209/224)
      5,449,216 100% 3.42MB/s 0:00:01 (xfr#16, to-chk=208/224)
      19,552,256 100% 5.30MB/s 0:00:03 (xfr#17, to-chk=207/224)
      5,474,304 100% 2.42MB/s 0:00:02 (xfr#18, to-chk=206/224)
      19,524,096 100% 6.87MB/s 0:00:02 (xfr#19, to-chk=205/224)
      3,952,128 100% 2.41MB/s 0:00:01 (xfr#20, to-chk=204/224)
      19,488,256 100% 3.77MB/s 0:00:04 (xfr#21, to-chk=203/224)
      3,673,600 100% 2.43MB/s 0:00:01 (xfr#22, to-chk=202/224)
      19,478,016 100% 4.07MB/s 0:00:04 (xfr#23, to-chk=201/224)
      4,618,752 100% 4.03MB/s 0:00:01 (xfr#24, to-chk=200/224)
      19,406,848 100% 6.13MB/s 0:00:03 (xfr#25, to-chk=199/224)
      5,358,592 100% 3.37MB/s 0:00:01 (xfr#26, to-chk=198/224)
      19,540,480 100% 4.61MB/s 0:00:04 (xfr#27, to-chk=197/224)
      4,749,312 100% 4.86MB/s 0:00:00 (xfr#28, to-chk=196/224)
      19,444,224 100% 3.89MB/s 0:00:04 (xfr#29, to-chk=195/224)
      4,443,136 100% 2.34MB/s 0:00:01 (xfr#30, to-chk=194/224)

      As you can see, it starts out great. Then (I guess) some kind of write buffer gets filled up and performance takes a dive... It is almost as if it was buffering the transfer on the SD card that I use for OMV itself, although I think that I've been able to rule that option out by monitoring the disk usage during transfer.

      My initial reaction was that this was just down to poor USB performance of the HC1 itself, but when I transfer files over the network to/from an SMB share on the thumb drive, I get reasonable USB 2 speed (~25 MB/s).

      Any ideas?

      Sorry If this thread went into the wrong forum category! Feel free to move it :-)
    • What filesystem are you using on the HDD and the thumb drive? If any is NTFS, FAT32 or exFAT (windows native filesystems), then try with EXT4 or some other Linux native filesystem. Seriously!

      Also remember that the USB port in the HC1 is USB2, not USB3. Use it for removable backup media. Don't use it for a shared folder on a data drive. Get a bigger HDD instead.
      OMV 4: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4
    • I was using BTRFS for the HDD and ext4 for the flash drive. Changed to ext4 on both and there is a noticeable difference. Transfers from USB to HDD now running at more than 20 MB/s and to the flash drive at ~10 MB/s, which is acceptable (although still somewhat disappointing).

      Seems like there was quite a performance penalty when transferring from one type of file system to another...

      Also, the USB port will of course only be used for offline backups. The SMB share was just for testing.

      Anyway, thanks for the suggestion!

      After some additional testing, it seems that the present ~10 MB/s cap is due to the USB 2 performance of the flash drive. So I guess that we could say, with quite certainty, that my initial problem was due to using two different file systems, and that I will probably experience full USB 2 speed as long as the drives involved are fast enough.

      Will try to remember to post an update once I get hold of a faster external drive.

      The post was edited 2 times, last by caps ().