Cannot enable write cache on RAID 10 with battery backed unit for HP GL380 G6

Y

yatesco

Well-Known Member
Sep 25, 2009
211
5
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Hi all,

Has anyone managed to turn on write caching for a HP GL380 G6? It is configured as RAID 10 over 4x300GB SAS drives and yes, the RAID card does have a BBU.

Trying to enable write cache gives:

sdparm --set=WCE /dev/cciss/c0d0p1
/dev/cciss/c0d0p1: HP LOGICAL VOLUME 2.50
mode select (10): transport: Host_status=0x0a [DID_PASSTHROUGH]
Driver_status=0x00 [DRIVER_OK, SUGGEST_OK]

change_mode_page: failed setting page: Caching (SBC)
Click to expand...

Copying large files in the VM nips along very very quickly (with virtio), but running a database app that does lots and lots of little reads and writes just crawls, and I am hoping it is because of this....
 
take a look on the HP documentation about configuration of the raid and BBU - I assume there is a management software.

like ASM.
 
Hi Tom,

Good point - I have installed the HP command line utils, and they do indicate write caching is enabled:
Code: 
=> controller slot=0 show config detail

Smart Array P410i in Slot 0 (Embedded)
   Bus Interface: PCI
   Slot: 0
   Serial Number: 50123456789ABCDE
   Cache Serial Number: PAAVP9SYIFWF
   RAID 6 (ADG) Status: Disabled
   Controller Status: OK
   Chassis Slot: 
   Hardware Revision: Rev C
   Firmware Version: 2.50
   Rebuild Priority: Medium
   Expand Priority: Medium
   Surface Scan Delay: 3 secs
   Queue Depth: Automatic
   Monitor and Performance Delay: 60 min
   Elevator Sort: Enabled
   Degraded Performance Optimization: Disabled
   Inconsistency Repair Policy: Disabled
   Post Prompt Timeout: 15 secs
   Cache Board Present: True
   Cache Status: OK
   Accelerator Ratio: 25% Read / 75% Write
   Drive Write Cache: Enabled
   Total Cache Size: 512 MB
   No-Battery Write Cache: Enabled
   Cache Backup Power Source: Batteries
   Battery/Capacitor Count: 1
   Battery/Capacitor Status: OK
   SATA NCQ Supported: True

   Array: A
      Interface Type: SAS
      Unused Space: 0 MB
      Status: OK

      Logical Drive: 1
         Size: 558.7 GB
         Fault Tolerance: RAID 1+0
         Heads: 255
         Sectors Per Track: 32
         Cylinders: 65535
         Stripe Size: 128 KB
         Status: OK
         Array Accelerator: Enabled
         Unique Identifier: 600508B1001037383941424344450400
         Disk Name: /dev/cciss/c0d0
         Mount Points: /boot 512 MB
         Logical Drive Label: AB3DA22250123456789ABCDE2B86
         Mirror Group 0:
            physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SAS, 300 GB, OK)
            physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SAS, 300 GB, OK)
         Mirror Group 1:
            physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SAS, 300 GB, OK)
            physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SAS, 300 GB, OK)

      physicaldrive 1I:1:1
         Port: 1I
         Box: 1
         Bay: 1
         Status: OK
         Drive Type: Data Drive
         Interface Type: SAS
         Size: 300 GB
         Rotational Speed: 10000
         Firmware Revision: HPDC
         Serial Number: 3SE199ED00009021NAZM
         Model: HP      DG0300FAMWN     
         PHY Count: 2
         PHY Transfer Rate: 6.0GBPS, Unknown
      physicaldrive 1I:1:2
         Port: 1I
         Box: 1
         Bay: 2
         Status: OK
         Drive Type: Data Drive
         Interface Type: SAS
         Size: 300 GB
         Rotational Speed: 10000
         Firmware Revision: HPDC
         Serial Number: 3SE182N800009020YPF2
         Model: HP      DG0300FAMWN     
         PHY Count: 2
         PHY Transfer Rate: 6.0GBPS, Unknown
      physicaldrive 1I:1:3
         Port: 1I
         Box: 1
         Bay: 3
         Status: OK
         Drive Type: Data Drive
         Interface Type: SAS
         Size: 300 GB
         Rotational Speed: 10000
         Firmware Revision: HPD5
         Serial Number: D001P9B055WU0945
         Model: HP      EG0300FARTT     
         PHY Count: 2
         PHY Transfer Rate: 6.0GBPS, Unknown
      physicaldrive 1I:1:4
         Port: 1I
         Box: 1
         Bay: 4
         Status: OK
         Drive Type: Data Drive
         Interface Type: SAS
         Size: 300 GB
         Rotational Speed: 10000
         Firmware Revision: HPD5
         Serial Number: D001P9B053ET0945
         Model: HP      EG0300FARTT     
         PHY Count: 2
         PHY Transfer Rate: 6.0GBPS, Unknown

I just don't understand the performance I am getting though :(

To put it into context, I have a java app which reads a couple of rows from a DB, does some stuff and then writes it to another DB - i.e. lots and lots of tiny reads and writes. If I run this on my Snow Leopard laptop running XP on VMWare desktop it runs over twice as fast on the writes then it does on the KVM virtual machine (windows 7). Both VMWare and the KVM box have 2G RAM, 1 vCPU and the drivers (Vmware tools and VIRTIO) installed. Both machines also have 'write cache' enabled on the guest (Win XP calls this 'configured for performance' I think).

The KVM machine absolutely flies through the reads but then lags way behind the Vmware on my crappy little laptop on the writes.

I even tried using tmpfs and creating a RAW file on that, but I see the same speed difference, which obviously means this is nothing to do with the RAID card, but I just out of options. I tried cache=none, and also tried the .32 and the .18 kernel but that didn't have any efect.

Any pointers gratefully received.....
 
please do not mix all in this thread (see subject). for new topics, create a new thread.

to test if the performance of the host hardware is good - use 'pveperf'
 
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