Re: Neil, bug in the minimum guaranteed patch?

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Fri, 11 May 2007, Justin Piszcz wrote:

> It worked for a while but this time I ran my raid check while doing an rsync, 
> for a while, it guaranteed 1MB/s but then:
>
> $ cat /proc/mdstat
> Personalities : [raid1] [raid6] [raid5] [raid4]
> md1 : active raid1 sdb2[1] sda2[0]
>      136448 blocks [2/2] [UU]
>        resync=DELAYED
>
> md2 : active raid1 sdb3[1] sda3[0]
>      55681216 blocks [2/2] [UU]
>      [============>........]  check = 62.1% (34605376/55681216) 
> finish=7.5min speed=46277K/sec
>
> md3 : active raid5 sdl1[9] sdk1[8] sdj1[7] sdi1[6] sdh1[5] sdg1[4] sdf1[3] 
> sde1[2] sdd1[1] sdc1[0]
>      1318686336 blocks level 5, 128k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
>      [=>...................]  check =  7.7% (11329412/146520704) 
> finish=45.5min speed=49515K/sec
>
> md0 : active raid1 sdb1[1] sda1[0]
>      16787776 blocks [2/2] [UU]
>
> unused devices: <none>
>
> It spiked back to 49MB/s its now 56MB/s -- something is wrong here.  The 
> rsync is now in dstate:
>
> root     18039 20.0  0.7  39200 30508 pts/9    D+
>
> Everything is very lagged, it is almost as if it is taking all of the 
> available resources for the check!
>
> Justin.
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Maybe not a bug in your patch rather-- but a bug somewhere, the scp was 
already running before the echo check > /sys/../sync_action took place, 
it worked for about 5-10 minutes and then the check took 100% precedence 
over the rsync.

Justin.