Re: how to sell network nodes

[L A Walsh]

On 2020/11/12 00:48, Michael J. Baars wrote:
> Hi,
>
> I needed to zero out my hard drive because one of my nodes has become unstable. 
> To this purpose I used coreutils dd with the following command line arguments
>
> dd if=/dev/zero of=/dev/mmc... status=progress
>
> and I noticed how slow this program is in doing the job. So I tried a couple of 
> different settings, like
>
> bs=1048576 oflag=direct
>
> but without significant improvement. The results are always the same... around 
> 25 mb/s.
>
> Then I remembered this little benchmark I write not so long ago, please do have 
> a look at it, it won't destroy your drive. I included the results obtained by 
> running the benchmark on the computer I'm currently working on, so you can 
> compare them to your own.
>   
---
   Your benchmark uses 'random' as input, which I seem to remember having
it's own slowness.

   Using '/dev/zero' as input, I immediately got 49MB/s.

   Ensuring the file was in 1 contiguous area on disk (used xfs_fsr) and
    "nfrags"
   I got     up to 56.1MB/s.

   Using a bs of 16MB and 4 blocks, I got up toe 64.3MB/s.

   Trying it on my larger RAID disk w/same sizes: 1.6MB/s.



> Hope that one of you feels inspired enough you to pick up the dd source codes 
> and finish the job.
>   
---
   Is that what you meant?

   All of those are rotating rust...the 1st disk is a
RAID5.  The larger Disk is a RAID10 with 6 stripes.