DL380 G5 with odd behaviour on Smart Array P400

[Antony Scerri]

Hi

I have a DL380 G5 with the Smart Array P400. New to this hardware sestup, so if you need more info let me know. Its running Windows 2003 64bit Enterprise (32Gb RAM). The current driver and firmwares versions are as follows:

SA P400 Win Driver : 6.8.0.64
SA P400 firmware : 4.06
DG146ABAB4 firmware : HPD7

I have 8 DG146ABAB4 drives installed. 3 Logical disk setup 2 logical drives mirrored, and a 3rd RAID 5. The controllers accelerator status is:

ACCELERATOR STATUS:
Logical Drive Disable Map: 0x00000000
Read Cache Size: 52 MBytes
Posted Write Size: 156 MBytes
Disable Flag: 0x00
Status: 0x00000001
Disable Code: 0x0000
Total Memory Size: 256 MBytes
Battery Count: 1
Battery Status: 0x0001
Parity Read Errors: 0000
Parity Write Errors: 0000
Error Log: N/A
Failed Batteries: 0x0000
Board Present: Yes
Accelerator Failure Map: 0x00000000
Max Error Log Entries: 12
NVRAM Load Status: 0x00
Memory Size Shift Factor: 0x0a
Non Battery Backed Memory: 0 MBytes
Memory State: 0x00

The drives dont have their indivudal write caches enabled.

So the odd behaviour im seeing and I just wanted to check if this was normal, as it seems really odd to me. I wrote a simple program just to check disk speed in writting data to the disk after noticing what i thought was slow app disk writes. The program create a 1GB file writting blocks of bytes at a fixed size per run. If the block size is close to 64KB (2^16 bytes) I get speeds up to 1300MB/s. If it writes blocks below that threshold its drop, so at 10KB block size its achieving 600MB/s (still generating a 1GB file). This I can understand and im ok with as it requires more writes).

However pushing the block size up to 200KB I only get 220MB/s max sometimes as slow as 90MB/s. Going above this its consitently slower. The average seems to be about 120MB/s when im writing blocks of 1MB at a time.

My question is why on earth does it achieve such slow rates when pushing larger blocks of data at it.

Thanks

Tony

[Gazy Gazy]

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