Poor write performance on smartarray 3200

[Patrick Müller]

Hello it's me again...
this time it's about the write performance of my raid 5 array...

read performance is absolutely ok, but the write throughput is never above 1,5 Mbyte/s...

there are 5 seagate hdds connected to the smartarray 3200, scsi channel 2, all are 80 pin sca drives in their bay,
The system is a quad processor pentium pro 200 MHz with 896 MB RAM

Has anyone any solution or idea for this?

TIA
Patrick

[JohnWRuffo]

Patrick:

It could be that the batteries are dead/low and the array accelerator is "disabled". During boot, do you get a 1793 or 1794 error on the screen?


If so, you can replace the accelerator board... take a look at the link below:
ftp://ftp.compaq.com/pub/supportinformation/techpubs/user_reference_guides/340862-002.pdf

[Patrick Müller]

thanks john for your answer, but the batteries are full and the array accelerator is enabled...

[amhakassa]

Hi Pat,

Have a look at this link if your server is one of the listed one in the link

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=PSD_EX001122_CW01

Good Luck

Regards
Amha Kassa

[Patrick Müller]

Hello Amha,

thank you for this tip but my server is not listed... it's a bull express 5800 MH server...

unfortunately they don't say why the i/o speed is decreased on these servers... that could have been of use...

i'll have to wait for another tip...

[Sanjay Kumar Suri]

Can you check the amount of Write cache? Can it be increased?

Have a look at this document as well.

http://www.docs.hp.com/hpux/onlinedocs/225852-001/225852e1a.pdf

sks

[Patrick Müller]

Hello Sanjay,

the ratio write/read is set to 50%... it can be increased, but with no effect...

the server acts as follows:

it receives data for example from the network... it stores it with full speed in ram until it's full. if data comes with 10MB/sec but the discs only write 1.5 MB/sec then the ram is soon full. then it continues to save the data onto the array with 1.5 MB/sec.

i can't imagine that the controller is so slow with writing into a raid 5 array...

thanks for your help... if anyone knows another solution feel free to write it here ;)

Patrick

[Patrick Müller]

any idea? anyone? =:-]

[Sanjay Kumar Suri]

You have a point. I am not sure further.

However, we keep the write cache at 70% (off course it is duplexed).

Can the total cache be increased?

sks

[Patrick Müller]

the total cache is fixed 64 MByte.

any idea welcome... ;)