CERC Performance Question

[Fred Skrotzki]

Inside a manufacturing line most of the time you can switch cards and be ok (Adaptec to Adpatec for example).  But I've had very little luck switching vendors, specially when the base chipsets change.  Each has it's own way of tagging and tracking the drives in a raid group.


-----Original Message-----
From: linux-poweredge-bounces at dell.com [mailto:linux-poweredge-bounces at dell.com] On Behalf Of Jean-Christophe Montigny
Sent: Wednesday, July 26, 2006 9:20 AM
To: ross levins
Cc: Grant.Sturgis at arraybiopharma.com; linux-poweredge at dell.com
Subject: Re: CERC Performance Question

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

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