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On Friday, 15 January 2021 08:42:16 GMT bobwxc wrote: |
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> 在 2021/1/15 下午4:27, Raffaele BELARDI 写道: |
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> >> -----Original Message----- |
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> >> From: bobwxc <bobwxc@××.com> |
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> >> Sent: Friday, January 15, 2021 08:57 |
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> >> To: gentoo-user@l.g.o |
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> >> Subject: Re: [gentoo-user] network transfer speed |
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> >> |
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> >> 在 2021/1/15 下午2:56, thelma@×××××××××××.com 写道: |
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> >>> On both of my systems the network card speed is showing 1000 |
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> >>> cat /sys/class/net/enp4s0/speed 1000 |
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> >>> |
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> >>> but when I do rsync larage file I only see about: 20 to 22MB/s On my |
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> >>> home network I get about 110MB/s between PC's |
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> >>> |
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> >>> Both PC's have SSD and the swith is Gigabit (I think). |
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> >>> How to find a the bottleneck? |
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> >> |
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> >> 1000Mbps network card's maximum theoretical speed is about 125MiB/s. |
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> >> It only works in short distances. |
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> > |
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> > Correct but that's the line speed that you'll never reach, when you take |
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> > into account Ethernet frame overhead, IP (and possibly TCP) header |
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> > overhead and application ( rsync, FTP, SMB, NFS) overhead you get lower |
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> > figures. In my experience 900Mbps (110MiBps) on a 1000Mbps line is more |
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> > realistic for 'normal' transfers. |
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> Yes, you are right. So it is just *theoretical* speed :-) |
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> |
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> I don't know where does the file he sync from. |
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> If you sync a file from a server in other city, for a 20 to 22MB/s speed |
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> is very normal. But if in home, that is not good. |
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> |
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> And for ftp and rsync. |
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> ftp is better for transferring a single large file once. |
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> rsync is better for a long-term, incremental synchronization. The |
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> file verification of rsync may take a lot of time for first sync. |
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|
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There is a theoretical network speed as already mentioned. There is a |
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protocol speed, which may limit throughput if it has e.g. heavy encryption/ |
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compression and the CPU is anaemic. Finally, there is a MoBo bus (SCSI/SATA/ |
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USB) and the media storage limit. If using USB 1.1 or 2.0 and/or the disks |
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are slow or experience write amplification, you'll find this will constrain |
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the final transfer speed significantly. |
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