On 09/07/2018 10:15 AM, William Oliver wrote: > > I've been reading the thread about backing up hard drives with > interest. I have a similar question. > > I have a 4 TB external USB hard drive that I've been doing backups on. > Unfortunately, it's starting to get a little flaky -- not being > recognized by my laptop, etc. The problem got better when I changed > enclosures, but now I'm a little paranoid that it might continue to > degrade. So... I'd like to copy the data to a new USB external hard > drive. > > The drive is about 96% full. > > I have tried plugging the old drive into a USB port, plugging the new > drive into a USB port and simply doing a cp -Ruav from one to the > other. It goes gangbusters for awhile, but after about 5 or 10 gigs, > it slows down to almost nothing. At the end of 8 hours of copying, > it's plugging along, but I only have about 400 gigs copied. > > I've searched the intertubes, and it seems that this is a problem > people have asked about across multiple distros. It is apparently > associated with some sort of cacheing issue in the kernel. > > Is there some solution to this? I tried rsync, but it was even slower. > I haven't tried dd, which was mentioned in the other thread; I might > give it a shot this weekend. But if there's a known fix for this, I'd > love to hear it.
It could be caching, but it's also possible that the two drives are on the same USB controller/hub. Plug the drives in and do an "lsusb -v" and verify that they're on separate USB hubs. It's important that they be on separate hubs to prevent contention issues. USB drives will be slower on writes due to cache flushes, filesystem updates and the like. I'd also try to put the target drive on a USB 2 or USB 3 port if possible as their write speeds would be higher than if they're on a USB 1.1 port. ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital [email protected] - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - - I don't suffer from insanity...I enjoy every minute of it! - ---------------------------------------------------------------------- _______________________________________________ users mailing list -- [email protected] To unsubscribe send an email to [email protected] Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/[email protected]
