On Friday, 15 January 2021 08:42:16 GMT bobwxc wrote: > 在 2021/1/15 下午4:27, Raffaele BELARDI 写道: > >> -----Original Message----- > >> From: bobwxc <bob...@88.com> > >> Sent: Friday, January 15, 2021 08:57 > >> To: gentoo-user@lists.gentoo.org > >> Subject: Re: [gentoo-user] network transfer speed > >> > >> 在 2021/1/15 下午2:56, the...@sys-concept.com 写道: > >>> On both of my systems the network card speed is showing 1000 > >>> cat /sys/class/net/enp4s0/speed 1000 > >>> > >>> but when I do rsync larage file I only see about: 20 to 22MB/s On my > >>> home network I get about 110MB/s between PC's > >>> > >>> Both PC's have SSD and the swith is Gigabit (I think). > >>> How to find a the bottleneck? > >> > >> 1000Mbps network card's maximum theoretical speed is about 125MiB/s. > >> It only works in short distances. > > > > Correct but that's the line speed that you'll never reach, when you take > > into account Ethernet frame overhead, IP (and possibly TCP) header > > overhead and application ( rsync, FTP, SMB, NFS) overhead you get lower > > figures. In my experience 900Mbps (110MiBps) on a 1000Mbps line is more > > realistic for 'normal' transfers. > Yes, you are right. So it is just *theoretical* speed :-) > > I don't know where does the file he sync from. > If you sync a file from a server in other city, for a 20 to 22MB/s speed > is very normal. But if in home, that is not good. > > And for ftp and rsync. > ftp is better for transferring a single large file once. > rsync is better for a long-term, incremental synchronization. The > file verification of rsync may take a lot of time for first sync.
There is a theoretical network speed as already mentioned. There is a protocol speed, which may limit throughput if it has e.g. heavy encryption/ compression and the CPU is anaemic. Finally, there is a MoBo bus (SCSI/SATA/ USB) and the media storage limit. If using USB 1.1 or 2.0 and/or the disks are slow or experience write amplification, you'll find this will constrain the final transfer speed significantly.
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