LSI 9271-8iCC, FastPath and RAID5 question

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istav555

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Apr 14, 2013
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I'm planning on setting up a RAID5 array with 4xIntel 520 480GB SSDs and a MegaRAID SAS 9271-8iCC card. FastPath will be enabled too.

What I'm not able to clearly understand from the online documentation of the LSI card is if I can add more drives to the RAID5 array in the future (without destroying and rebuilding the array of course). Googling also didn't help much...

Does anybody know about this?

Thanks
 

istav555

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Apr 14, 2013
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I now have the card and the drives and I'm doing some tests.

It seems that the LSI card has this amazing limitation with OCE: If you have 2 virtual drives on your array (for example a 100GB system drive and the rest space as the second drive) you can't use OCE! It's just not possible with MegaRAID Storage Manager or with WebBIOS...

If you have one virtual drive on your array then no problem, OCE works perfectly! With 2 drives the options to do the OCE just aren't there.

Firmware has been updated to the latest version too but issue not solved.

My main problem with that is that I do not want a huge 2TB+ system partition because I will have to use GPT and I do not want to do that with a Windows system drive.

If anyone has a different experience than mine then please feel free to post here.

For the time being I guess I'll have to use two close-to-2TB partitions. (I will eventually use 8 480GB SSDs with this)
 

mobilenvidia

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Sep 25, 2011
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Have you setup a 4x480GB RAID5 array ?
Then partitioned this array into a small boot and the rest data ?

I don't think OCE will allow OCE on arrays that are bootable, as when it did expand it would cause mayhem with OS
You need to setup a boot Array and a data array then you should be able to add drives to the data array.
If you already tried this then ignore what I just said
 

istav555

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Apr 14, 2013
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Have you setup a 4x480GB RAID5 array ?
Then partitioned this array into a small boot and the rest data ?
Yes, this is my setup. Except that when I'm trying out OCE I have assigned 3 drives to RAID5.


I don't think OCE will allow OCE on arrays that are bootable, as when it did expand it would cause mayhem with OS
You need to setup a boot Array and a data array then you should be able to add drives to the data array.
If you already tried this then ignore what I just said
There's actually no problem in expanding a boot virtual drive/array. I already did that, twice actually. The LSI Storage Manager allows this and it also is no problem for Windows.

You just have to expand the system drive's capacity in Windows' Disk Management which is completed in 2 seconds.
 

mobilenvidia

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Sep 25, 2011
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If you are adding a drive to an existing array in MSM or web-bios it will take ages.
It has to realign the new drive into the array, all the data needs to be read then written back to drive to insert (or remove) drive from array.

Windows to adjust to new array size will take but miliisecs
 

istav555

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Apr 14, 2013
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If you are adding a drive to an existing array in MSM or web-bios it will take ages.
It has to realign the new drive into the array, all the data needs to be read then written back to drive to insert (or remove) drive from array.

Windows to adjust to new array size will take but miliisecs
It doesn't really matter how long it takes as long as it can be done online and not require an array rebuild.

FWIW with a pretty much empty array (about 100GB used) it takes about 20-25 minutes to add the drive.
 

istav555

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Apr 14, 2013
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How does the controller know how much of the array is used?
Oh, you mean during OCE? Didn't thought of that, does it work on the block level? If it does then it's even better for my case. If it took less than 30 minutes now it should do around the same time in the future I guess...
 

omniscence

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Nov 30, 2012
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Normally OCE (and everything else the controller does) would work on block level. I would assume that the controller has to completely rewrite ALL drives for that. It would take hours to days for harddisks, but for SSDs it may work that fast. Depending on the SSD controller and the internal overprovisioning this may severly reduce the performance if done often.
 
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istav555

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Apr 14, 2013
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Yes, it most surely is not a quick task with HDs. However, it's ok with SSDs.

As for performance degradation it doesn't really matter. These are consumer grade SSDs and with such low $/GB you can throw in another one when that happens.