Re: [gentoo-user] Intel(R) C600 SAS Controller

["Stefan G. Weichinger" <lists@xunil.at>]

Am 11.06.2014 22:17, schrieb thegeezer:
> On 06/11/2014 07:57 PM, Stefan G. Weichinger wrote:
>> looks promising:
>>
> 
> awesome.  i did have a look through the diff, there are lots of scsi
> drivers selected, storage (block) cgroups but i think the crucial factor
> was the HZ was set at 100 previously and 1000 now.  i guess it has
> helped kernel-io though maybe a kernel hacker in here might give a more
> authoritative answer


The help suggests to choose 100 for servers ... the 1000 comes from the
sysresccd-setup, yes.

I wonder if chosing the "Processor Family" also had an influence.

And I even wonder more if I have some bad choices in my desktop's kernel
as well ;-) it's a grown setup over years ...

For now it looks good ... I will configure the current kernel as a
fallback kernel and maybe play with some options.


>> One big fat hw-RAID10 might be better?
>> But losing the wrong 2 drives makes it crash again ... afaik.
> yeah you could argue with raid6 you can _only_ lose two disks, whereas
> if you lose the right disks with raid01 you can lose 3 and still rebuild.
> raid 0+1 (as opposed to raid10, slightly different) gives you great
> speed and at least one drive you can lose.
> however, you are not protected by silent bit corruption but then you are
> using btrfs elsewhere.

... for the OS, yes ... and maybe for the target of virt-backup.

> myself i would use lvm to partition and then at least you can move
> things around later; btrfs lets you do the same afaiu
> _always_ have your hotspare in the system, then it takes less time to
> come back up to 100%
> nothing is quite as scary as having a system waiting on the post and a
> screwdriver before rebuild can even start

good suggestion, sure.

That would mean rebuilding the arrays to a RAID6 over 4 or 5 disks and
keeping one aside.


>> time for a break here.
> i'd strongly recommend such monitoring software as munin to have running
> -- this way you can watch trends like io times increasing over time and
> act on them before things start feeling sluggish

I will take a look into it and check how much time I need to learn and
set up.

> well earned break :)

;-)

S