HP DL380 G6 + P411/512MB + D2600 Enclosure slow

[Andreas Schier]

Hello all,

we have the above hardware here. The D2600 is a 6Gb/s enclosure with 12 x 600GB (6Gb/s) harddrives. It´s connected to a Smart Array P411 with battery pack (512MB) and Raid 6. The read performance is like a dream. Approx. 800MB/s per second. But the write performance is poor. If i´m transfering data to the enclosure it starts with approx. 800MB´s too, but after a a few seconds it falls down to 150-200MB/s. All components have the newest firmware. I testet it with Windows 2003 Server and Novell Netware 6.5 SP8. All with the same issue.

Any idea ?

Thanks in advance
Andreas

[TTr · Accepted solution]

> it starts with approx. 800MB´s too, but after a a few seconds it falls down to 150-200MB/s.

Ususally that is the effect of cache saturation. Initially the writing is going in the cache and it is very fast. When the cache fills up it needs to be written out to the drives before anymore data can be written out. After that point you rely on the actual drive speed for the writing.

You may want to try fewer drives in your raid groups to see if you might get some improvement.

If you will be doing sustained writing (large amounts of data), then this is what you should expect. For more casual writing activity, you will be utilizing the cache and will get better performance.

If you do sustained reading, you will se similar behavior.

Check your cache settings (read/write ratio). You may want to change those based on the type of i/o (read vs write).

[Andreas Schier]

Hello thanks for you answer.

I played with the settings in the controller. But the issue is the same. Very fast reading but bad writing. We bought this enclosure because we need much power. But in the moment this enclosure is slower then a MSA60. So anything must be wrong. Before 3 days i configured the Volume and since this time the process Drive Array â Disk Performance Optimization Scan in Progress RAID 4/5/ADG performance is running and runnig. I never seen it runnig so long. This server is attached with 10Gigabit to a HP core. At this core i attached 4 Macintosh all with 1Gigabit. It takes 20minutes!!! to copy 14GB (14GB each Macintosh) data from the macs to the D2600 Enclosure. I can´t imagine that the read performance is 5 times better then the write performance.

Any idea
Andreas

[TTr]

Do you use all 12 drives in your arrays? Have you tried fewer drives, maybe 2 arrays of 5-6 drives each? Too few or too many drives in an array can cause i/o starvation or i/o contention.

Did your msa60 have the same number of drives in its arrays?

Another topic to explore is if the p411 supports dual domain connectivity like the p800. That will double the i/o bandwidth to the 2600.

[Andreas Schier]

Hi,

yes i made three arrays with 4 drives per array. Then i created 3 logical volumes with Raid 6. Each volumes is approx. 1,9TB in size. That´s the only way, because we are using Novell Netware 6.5 at it can´t handle physical partions more then 2TB in size. In Netware we combine the three partitions to one logical volume. I made a test where i´m using only one array with 4 drives. But the speed was poor, too.
The MSA60 is configured the same. Three arrays and combine to one logical volume in Netware.

But now let´s talk about the important thing with the dual domain. I didn´t understand this. Our D2600 enclosure has two I/O modules. In this time i have only one cable from Port1 (P411 controller) to Port1 from the enclosure (upper I/O Module). When i attached the second cable from Port2 (P411) to the the second I/O Module the server shows an error. "It´s not supported with this firmware". But i have the newest one (V2.272). In the manual are some pictures with cabeling examples. But nothing shows a example for Dual Domain support. The drives are able to use for Dual Domain. So i think my cabeling is wrong.

Any idea.
Thank you so much for help.

Andreas

[TTr]

Dual domain is probably not supported with the P411. I looked for any documentation and could not find any. The P800 has the dual domain support option. You connect both SA connectors to the MSA and you double the i/o. I don't know why HP did not put this feature in the P411 yet.

[TTr]

Dual domain also relies on having dual port SAS drives. (all drives today are dual port drives). If you have 2 arrays of 5-6 drives each, the controller can do i/o concurrently on both channels and both arrays. There are many documents that mention it. There is one document that explains dual domain in detail but it did not come up in the search. I have that document in my office PC I will send it to you on Monday as a reference.

In the meantime keep looking around, you might find something that will help i/o, I just don't know what. Good luck.

[TTr]

Here is the dual domain doc.

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01451157/c01451157.pdf?jumpid=reg_R1002_USEN

[Bruce W. Seaman]

did you enable the write cache on local drives in the bios, also, when you create the array you need to set the percentage of read\write performance, and then enable the write cache on the controller itself....this will help tremendously, these servers come in with write cache disabled, and 100% of the cache dedicated to Read.

[Andreas Schier]

Hello,

thank you both for your replies. It was hard to figure out what was the problem. The tip with the Dual Domain was very interresting. But i got the information that the P411 Controller doesn´t support Dual Domain in the moment. If in the future i don´t know. But the reason for the really poor performance is Netware 6.5. With Linux Enterprise Server 10 it runs like i want. So i don´t know if the drivers for Netware are poor. But we have time pressure to set up the new server. So we take Linux and we are happy now.

Thank you very much.
Andreas