[CentOS] ssd quandry

Tue Oct 25 09:47:54 UTC 2011
John R Pierce <pierce at hogranch.com>

On 10/25/11 2:16 AM, John Doe wrote:
> Just wondering how come the array is detected as /dev/sd* instead of the classical /dev/cciss/c0d*...
> Is the P411 a fake raid?

no, its a seriously fast pci-e SAS2 hardware raid.   the physical 
devices don't show at all.  it has 1GB of writeback cache thats backed 
by flash with a supercap, instead of the traditional battery that dies 
in 3 years.

I didn't have to install any special drivers to use it, C6 just saw it 
as-is, /dev/sda is a raid1 of disks 0,1, /dev/sdb is a raid10 of disks 
2-22, and sdc is a raid0 of SSD 23,24 (disk 25 is a hot spare for sda,sdb)

its configurable with the hpacucli command tool I got from HP's site.

# lspci -vnn -s 6:0.0
06:00.0 RAID bus controller [0104]: Hewlett-Packard Company Smart Array 
G6 controllers [103c:323a] (rev 01)
         Subsystem: Hewlett-Packard Company Smart Array P410 [103c:3243]
         Flags: bus master, fast devsel, latency 0, IRQ 24
         Memory at fbc00000 (64-bit, non-prefetchable) [size=2M]
         Memory at fbbff000 (64-bit, non-prefetchable) [size=4K]
         I/O ports at d800 [size=256]
         Expansion ROM at fbb00000 [disabled] [size=512K]
         Capabilities: [40] Power Management version 3
         Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
         Capabilities: [70] Express Endpoint, MSI 00
         Capabilities: [ac] MSI-X: Enable+ Count=16 Masked-
         Capabilities: [100] Advanced Error Reporting
         Kernel driver in use: hpsa
         Kernel modules: hpsa

# hpacucli ctrl slot=1 show detail

Smart Array P410 in Slot 1
    Bus Interface: PCI
    Slot: 1
    Serial Number: PACCRCN810E1R9J
    Cache Serial Number: PBCDF0CRH0Q13H
    RAID 6 (ADG) Status: Disabled
    Controller Status: OK
    Hardware Revision: Rev C
    Firmware Version: 5.12
    Rebuild Priority: Medium
    Expand Priority: Medium
    Surface Scan Delay: 15 secs
    Surface Scan Mode: Idle
    Queue Depth: Automatic
    Monitor and Performance Delay: 60 min
    Elevator Sort: Enabled
    Degraded Performance Optimization: Disabled
    Inconsistency Repair Policy: Disabled
    Wait for Cache Room: Disabled
    Surface Analysis Inconsistency Notification: Disabled
    Post Prompt Timeout: 0 secs
    Cache Board Present: True
    Cache Status: OK
    Accelerator Ratio: 25% Read / 75% Write
    Drive Write Cache: Disabled
    Total Cache Size: 1024 MB
    No-Battery Write Cache: Disabled
    Cache Backup Power Source: Capacitors
    Battery/Capacitor Count: 1
    Battery/Capacitor Status: OK
    SATA NCQ Supported: True

dunno if that helps?

since I got it sorted out with 4k blocks and XFS, I'm seeing about 12000 
write IOPS via pgbench to that sdb raid10, and 16000 wr/s to the sdc SSD 
raid1, these are both pretty close to flat out for the disks.  sustained 
writes from iozone hit 1.2GB/sec on sdb and 800MB/s on sdc, also pretty 
much hardware bandwidth of the disks.

john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast