CERC Performance Question

[Sturgis, Grant]

Jean-Christophe Montigny wrote:
> Hello,
> 
> In this case, I have a $.02 question for you :
> Is it possible to remove the CERC controller and put another controller 
> in the machine to access the RAID5 volume, that was created by the cerc 
> controller ?
> Is it a "standard" way to manage raid5, or is it in some way proprietary 
> to the controller card ?

I don't have a way of doing this (a spare card).  Dell tech support is 
looking at this...

One interesting thing we found is that `modinfo aacraid` does not 
mention CERC SATA:

# modinfo aacraid | more
....
description:    Dell PERC2, 2/Si, 3/Si, 3/Di, Adaptec Advanced Raid 
Products, and HP NetRAID-4M SCSI driver
....

> 
> Thanks,
> 
> JCM
> 
> ross levins a écrit :
> 
>> To remove any issues with NFS and/or network why dont' you just try 
>> your test by writing/reading locally for read and write test
>> dd if=/dev/zero of=big_file bs=1024 count=5120000
>> dd of=/dev/zero if=big_file bs=1024 count=5120000
>>
>> I have seen read/writes upto 80 to 90MB/second with this controller 
>> which also is too slow and in general this controller performs poorly.
>> thanks
>>
>>> From: "Sturgis, Grant" <Grant.Sturgis at arraybiopharma.com>
>>> To: linux-poweredge at dell.com
>>> Subject: Re: CERC Performance Question
>>> Date: Tue, 25 Jul 2006 08:41:37 -0600>
>>> Can anyone comment if these numbers look normal or not?
>>>
>>> Thanks.
>>>
>>> Sturgis, Grant wrote:
>>> > Greetings List,
>>> >
>>> > I am experiencing very poor performance with a CERC SATA 1.5/6ch RAID
>>> > card wtih firmware v4.1-0.  Four disks are configured in RAID 5 and 
>>> the
>>> > OS is RHEL ES 4.0.  I understand that this is not a high performance
>>> > RAID card or RAID configuration (write penalty associated with RAID 
>>> 5),
>>> > but this just seems ridiculous.
>>> >
>>> > Created a 5GB file with the command:
>>> >
>>> > dd if=/dev/zero of=big_file bs=1024 count=5120000
>>> >
>>> > and then timed a move operation from an NFS mount to the local RAID
>>> > array connected at 1000Mbps end-to-end:
>>> >
>>> > time mv /hosts/server/test/big_file local_test_folder
>>> >
>>> > and the results were:
>>> >
>>> > 0.623u 34.342s 9:44.65 5.9%     0+0k 0+0io 3pf+0w
>>> >
>>> > This is over 10 minutes to move that much data over a gigabit
>>> > connection.  What's even worse is that the load average on the system
>>> > exceeded 18 resulting in an unusable system for all other users.  
>>> There
>>> > was no response to any commands or login attempts.
>>> >
>>> > Does this seem reasonable to you?  What can I do to improve this
>>> > performance (short of doing away with RAID 5)?
>>> >
>>> > Any comments and suggestions are very much appreciated.
>>> >
>>> > Thanks,
>>> >
>>> > Grant
>>> > ----------------
>>> >
>>> >
>>> >
>>> >
>>> > Pardon this rubbish:
>>> >
>>>
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