On Tue, Aug 09, 2022 at 02:21:21PM +0200, Christian Weisgerber wrote: > Moving 9TB with dump|restore from an old hard disk to a bigger one > reminded me again that dump(8) is, well, slow: > > DUMP: 9104433830 tape blocks > DUMP: Date of this level 0 dump: Sat Aug 6 16:36:52 2022 > ... > DUMP: Date this dump completed: Tue Aug 9 13:51:01 2022 > DUMP: Average transfer rate: 36530 KB/s > > That is far below the read-write speed of a modern SATA drive. > systat(1) clearly showed that the source disk and dump(8) was the > bottleneck, not the target disk and restore(8). Too much seeking?
Ok. But what is a theoretic speed limit for this device? If I do something like this on my laptop w/ssd: # date +'%s'; dd if=/dev/sda2 of=/dev/null bs=1024 count=$((512*1024)); date +'%s' 1660089697 521565184 bytes (522 MB, 497 MiB) copied, 2 s, 261 MB/s 524288+0 records in 524288+0 records out 536870912 bytes (537 MB, 512 MiB) copied, 2,06702 s, 260 MB/s 1660089699 I tried it with reading first 512 megs, for you, since you want to deal with terabytes, count= would need to be adjusted, say, 100 gigs? Reasoning: the specification for sata says one thing, but it says theoretical upper speed, if I am correct. So you want to know about real speed limit of _this_ device. -- Regards, Tomasz Rola -- ** A C programmer asked whether computer had Buddha's nature. ** ** As the answer, master did "rm -rif" on the programmer's home ** ** directory. And then the C programmer became enlightened... ** ** ** ** Tomasz Rola mailto:tomasz_r...@bigfoot.com **
