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Old 10-28-2004, 05:20 AM   #1
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Question SATA Raid with Dell/Adapter 6ch card performance issue under RedHat ES 3.0


here is another performance issue thread

I've just bought a new Dell PowerEdge 1800, with dual XEON 2.80GHz and hyperthreading activated, 3GB memory and the Dell/Adapter RAID SATA 6 channels card with 6 Maxtor SATA 160 drives.

The system is running RedHat ES 3.0 aka Linux 2.4.21-4.ELsmp ehci-hcd Intel Corp. 82801EB USB2

The system went with just one big Array of 6 discs in Raid 5, 64K strips

I've noticed poor disc transfer rate and here's some data:

[root@groville root]# vmstat
procs memory swap io system cpu
r b swpd free buff cache si so bi bo in cs us sy wa id
0 0 0 18340 9336 2888196 0 0 17 6 22 36 2 19 17 62

[root@groville root]# uptime
21:21:28 up 1 day, 23:07, 3 users, load average: 0.04, 0.13, 0.31

[root@groville root]# hdparm -tT /dev/sda

Timing buffer-cache reads: 3796 MB in 2.00 seconds = 1898.00 MB/sec
Timing buffered disk reads: 60 MB in 3.02 seconds = 19.87 MB/sec

[root@groville root]# lsmod|grep aacraid
aacraid 43380 7
scsi_mod 116904 5 [sr_mod sg aacraid mptscsih sd_mod]

[root@groville root]# dkms status|grep aacraid
aacraid,, 2.4.21-4.ELsmp: installed (original_module exists)

20MB/s with 100% iowait and systems hangs on such a system is really

Of course DELL Support is trying to explain me that with a 133MB/s bus, it's normal, I'm a bit surprised

So my question is:

while reading sites like Speeding up Linux Using hdparm by Rob Flickenger, I think it's possible to tweak my system...

is there anyone experiencing such problems, I mean, system hanging for 3 to 30 seconds while transferring data (400% iowait in my case) and so poor data transfers?

Kind Regards

Last edited by jwernert; 10-28-2004 at 05:22 AM.
Old 06-08-2005, 01:47 AM   #2
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Registered: Nov 2004
Distribution: Mandriva mostly, vector 5.1, tried many.Suse gone from HD because bad Novell/Zinblows agreement
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Newbee here, but some experience with raid0 2 sata drives
of 160 Gb (posted in LQ) benchmarked with tiobench.

Have you looked if you HDs are not blacklisted in
the source code of aacraid.c?

In my experience (long thread on that) hdparm does really
work well with sata drives

In you syslog and / or dmesg what does it say about
your sata drives detection: are they recognised as ATA100
If yes this is good.

No idea about the iowait, does not look normal
Old 07-06-2005, 01:46 AM   #3
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Hi jwernert,

I have a similar configuration with yours. My server is Dell PowerEdge 1800, dual XEON 3.00GHz, 2GB memory and the Dell/Adapter RAID SATA 6 channels card with 6 SATA 150 HDs.

Since the server have just been purchased and I am new to the RAID configuration and monitoring, I am trying to test for RAID 1. The configuration of RAID 1 is OK. RAID 5 is my target approach.

The DRAC Card was not purchased.

The target server OS is Redhat Linux Enterprise AS 4. However, the supported OS verion for Redhat Linux Enterprise is only up to 3, with reference to the enclosed setup CD's documentation.

Now, I have two problems:

1. How to monitor the server health status and perform administrative tasks remotely without installing DRAC Card? As far as I know, the Server Administrator can do the task. However, I could not access the server with using a browser on port 1311. The OS is the Redhat Linux Enterprise 3. It had response and asked me to download an unknown file. The file name was different for each time when I tried to access. I guess the server port 1311 was being used by the Server Administrator.

2. When I install Redhat Linux Enterprise AS 4, the ethernet card could not be recongized. Even I downloaded and installed the driver that was downloaded from Dell's support site with no dependency, the ethernet card was displayed in the Hardware Browser, but could not be configured.

I would be appreciate if you or anyone give me a helpful suggestion. Thanks a lot!



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