[Linux-PowerEdge] poor disk IO - suggestions please?

David Hubbard dhubbard at dino.hostasaurus.com
Mon Jul 22 09:17:16 CDT 2013


The H200 is definitely not very good; can you run software
mirror instead of using it?  I have a set of those same
drives in a R410 with the on-board SATA doing software
raid on CentOS 6 and I'm seeing really great performance;
100+ MB/sec writes.

I'd definitely enable the write back cache, and set it to
read ahead, not read ahead adaptive.  I found on the H200
the read ahead adaptive works against you rather than for you.

David

> -----Original Message-----
> From: linux-poweredge-bounces at dell.com 
> [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Faris Raouf
> Sent: Monday, July 22, 2013 9:15 AM
> To: linux-poweredge at lists.us.dell.com
> Subject: [Linux-PowerEdge] poor disk IO - suggestions please?
> 
> Dear all,
> 
>  
> 
> I'm running a couple of R210 IIs with mirrored 
> non-Dell-certified WD "Black" 500Gb 72k SATA on an H200 
> controller, with the write cache NOT enabled in OMSA.
> 
>  
> 
> Disk performance in general always seemed sluggish on these 
> compared to my older R200s, but now it has started to become 
> a serious problem, with high IO Waits resulting in 
> increasingly annoying issues for certain UDP-reliant 
> applications, particularly when we initiate backups. This 
> just didn't happen on the older machines.
> 
>  
> 
> I'm running a RedHat 6-derived 2.6.32-042 kernel (Parallels 
> Virtuozzo) on the R210 IIs and using the stock kernel mpt2sas driver.
> 
>  
> 
> I'm wondering if there would be a benefit to installing the 
> dell-supplied mpt2sas driver as opposed to using the stock 
> kernel driver. Can anyone offer any advice on this please? 
> 
>  
> 
> The kernel driver version is "12.101.00.00", while the latest 
> Dell driver for RH6 (64bit) is "07.00.01.00-1" and while 12.x 
> is higher than 7.x, I can't assume the version numbers are 
> necessarily actually comparable, hence my question here. I'm 
> also concerned that the dell driver may be more tuned to 
> dell-certified drives than the stock kernel driver.
> 
>  
> 
> # modinfo mpt2sas
> 
> filename:       
> /lib/modules/2.6.32-042stab076.8/kernel/drivers/scsi/mpt2sas/m
> pt2sas.ko
> 
> version:        12.101.00.00
> 
> description:    LSI MPT Fusion SAS 2.0 Device Driver
> 
> author:         LSI Corporation <DL-MPTFusionLinux at lsi.com>
> 
> vermagic:       2.6.32-042stab076.8 SMP mod_unload modversions
> 
>  
> 
>  
> 
> I'd love to enable the write cache (data centre has usual UPS 
> + diesel generators) but I'm somewhat worried about potential 
> data loss/corruption if I do - am I being over-cautious here? 
> 
>  
> 
> Switching to 10k or 15k SAS drives would be nice, but our 
> budget prevents it L
> 
>  
> 
> I've also read an awful lot of posts in various places about 
> how the H200 isn't great and so on, but that's what I've got 
> so I have to make the best of it. 
> 
>  
> 
> Any suggestions/hints would be appreciated!
> 
>  
> 
>  
> 
> 



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