MSA30 Raid 10 Dual Bus questions

[Timothy DiBenedetto_1]

We are currently exploring swapping our current Raid 5 configuration on our 6402/MSA30 setup to a Raid 1+0.

In our test environment, I have setup the new raid level, but the drive utilization we are seeing is concerning.

It appears it has built the mirror across channels in the dual bus setup, such that all the reads are occurring on channel 1, and it mirrors over to channel 2. This leads me to believe 1/2 our bus bandwidth is sitting idle 90% of the time (its a high read environment).

I don't seem to be able to lay the drives out in a way that it will split the raid across the buses differently. I've explored re-ordering them in saconfig but that doesn't seem to work (and is backed up by a post I've found here).

I'm looking for a way to utilize both buses and optimize the throughput. At this point, it appears the only way to get it to work would be creating 2 raid 10s and force-feeding them into each bus side.

[Torsten.]

Since you say "saconfig" - do you run hp-ux?

Post the saconfig output to show us your configuration.

[Timothy DiBenedetto_1]

I didn't think to put the OS in since I was posting in the HP-UX sysadmin forum.

Yes, HP-UX 11.23

here is the saconfig output

raptor # saconfig /dev/ciss4

******************** SmartArray RAID Controller /dev/ciss4 ********************

Auto-Fail Missing Disks at Boot = enabled
Cache Configuration Status = cache enabled
Cache Ratio = 25% Read / 75% Write

---------- PHYSICAL DRIVES ----------

Location Ch ID Size Status

External 1 0 300.0 GB OK
External 1 1 300.0 GB OK
External 1 2 300.0 GB OK
External 1 3 300.0 GB OK
External 1 4 300.0 GB OK
External 1 5 300.0 GB OK
External 1 8 300.0 GB OK
External 2 0 300.0 GB OK
External 2 1 300.0 GB OK
External 2 2 300.0 GB OK
External 2 3 300.0 GB OK
External 2 4 300.0 GB OK
External 2 5 300.0 GB OK
External 2 8 300.0 GB OK

---------- LOGICAL DRIVE 0 ----------

Device File = c4t0d0
RAID Level = 1+0
Size = 1716586 MB
Stripe Size = 128 KB
Status = OK

Participating Physical Drive(s):

Ch ID

1 0
1 1
1 2
1 3
1 4
1 5
2 0
2 1
2 2
2 3
2 4
2 5

Participating Spare Drive(s):

None

---------- LOGICAL DRIVE 1 ----------

Device File = c4t0d1
RAID Level = 1+0
Size = 286097 MB
Stripe Size = 128 KB
Status = OK

Participating Physical Drive(s):

Ch ID

1 8
2 8

Participating Spare Drive(s):

None

[Torsten.]

It's a SA640x, right?

IIRC it is the default, mirror one channel to the other because of availability. But I'm not really sure if the performance would be better if the controller would do this in a different way. Maybe (!) a plain LVM (striped) mirror would do the job faster (without this smartarray controller, but using "normal" SCSI controllers instead) ...

[Timothy DiBenedetto_1]

yes, a 6402.

Watching the MSA as it is reading, only channel one has any disk activity, so the entire throughput on channel 2 is being ignored by the card.