CERC Performance Question

[Jean-Christophe Montigny]

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 ?

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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-- 
Jean-Christophe Montigny
Elève de troisième année à Grenoble Ecole de Management
Actuellement en parcours ingénieur à l'Ecole Nationale Supérieure de 
Télécommunications de Bretagne