# Re: AWFUL reshape speed with raid5.

- From: Justin Piszcz \<hidden\>
- Date: 2008-07-28 18:14:21 
- List: linux-raid
- Page: https://ratatoskr.run/linux-raid/2008/07/6603573
- Thread: https://ratatoskr.run/linux-raid/2008/07/6603571/t.md

```text
What happens if you use 0.90 superblocks?

Also, are these sata ports on the mobo or sata ports on a pci-based mobo?

On Mon, 28 Jul 2008, Jon Nelson wrote:

> I built a raid5 with 2 devices (and --assume-clean) using 2x 4GB
> partitions (not logical volumes).
> I then grew it to 3 devices.
> The reshape speed is really really slow.
>
> vmstat shows I/O like this:
>
> 0  0    212  25844 141160 497484    0    0     0   612  673 1284  0  6 93  0
> 0  0    212  25164 141160 497748    0    0     0    19  594 1253  1  4 95  0
> 0  0    212  25044 141160 498004    0    0     0     0  374  445  0  1 99  0
> 1  0    212  25220 141164 498000    0    0     0    23  506 1149  0  3 96  1
> 0  0    212  25500 141164 498004    0    0     0     3  546 1416  0  5 95  0
>
> The min/max is 1000/200000.
> What might be going on here?
>
> Kernel is 2.6.25.11 (openSUSE 11.0 x86-64 stock)
>
> /proc/mdstat for this entry:
>
> md99 : active raid5 sdd3[2] sdc3[1] sdb3[0]
>      3903744 blocks super 1.0 level 5, 64k chunk, algorithm 2 [3/3] [UUU]
>      [=>...................]  reshape =  8.2% (324224/3903744)
> finish=43.3min speed=1373K/sec
>
>
> This is on a set of devices capable of 70+ MB/s.
>
> No meaningful change if I start with 3 disks and grow to 4, with or
> without bitmap.
>
> -- 
> Jon
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```