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_rola@bigfoot.com **
No comments:
Post a Comment