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Doubts about expansions and RAID


alermto
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Hi everybody,

 

this is my first post and I would like to start by thanking you all for making this forum great. I red many of the pages and posts linked here and managed to make a general idea of what I want to do - but still have some questions.

 

I have a N40L with a 2TB disk for storage and a 500GB one for the OS. The latter has already been moved to the ODD bay in order to leave the non-hot plug ones available for future expansion.

 

And now the time for "future expansion" has come :-) I would like to use 5 HDDs for storage and find a different solution for the OS. These are my ideas, and please correct me if I'm getting something wrong:

 

4 HDDs x 3TB in the 4 non-hot plug bays (for storage)

1 HDD x 3TB in the ODD bay connected to the internal SATA port using the modified BIOS to get it working at full speed (for storage)

1 SDD x 250GB under the ODD bay (would it have enough room?) connected to the eSATA port on the back (for the OS)

 

My questions:

 

1. Would ALL the 5 HDDs belong to the same RAID array (in this case I'm still wondering about RAID-0 or RAID-1)? Obviously my doubt is about the disk connected to the internal SATA port.

 

2. This is more technical. Does RAID also mean that all the disks are seen as one by the OS?

 

3. Would the eSATA port allow me to use the SSD as the OS disk to boot from? If that would be the case, would it go at full speed? If not, should I use the USB port to host the OS? Would every OS be suitable for this solution? It would decrease performance, wouldn't it?

 

Please consider that I have quite a good general experience on this things so I think I'd be able to apply any solution you suggest, once my doubts are overcome :-) And on the other hand please point out every silly nooby thing I might have said :-)

 

Thank you all guys!

 

Alessandro

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Ciao Bella and Welcome.....

 

With the 5x3TB drives you could have one large RAID5 array or a RAID1 (with 2 drives) and a RAID5 (with 3 drives).  RAID means the drives are seen as one "logical drive" by the OS so you would either see one logical drive or two based on the configuration.

 

I would not try to host the OS from the USB.  There are six possible drive connections so you could either use the eSATA port for the OS or the onboard SATA port for the OS.

 

 

Hope this helps.

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Thank you very much for your reply. I would like to go for one large RAID5 system, but I think the hardware RAID system of the N40L only supports RAID0 and RAID1. Is a software RAID5 less reliable or performing than a hardware one?

 

I was also thinking about RAID0, which would be quite a risky option but would also maximize my HDD capacity, which I'm prioritizing.

 

Anyway, there is still that question about the 5th HDD being put together with the other 4 non-hot plug ones to form a unique RAID array. It seems to me that the internal SATA port is not directly linked to the RAID hardware system in the N40L, so I thought the maximum I could obtain is a RAIDwhatever with 4 HDDs and a sole HDD (the fifth one) in a non-RAID configuration. Is that the case? I'm insisting on this point because I have a strong interest in making the OS see a unique large logical volume! ;-)

 

Thank you very much again for your help!

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True.  You would have to add a Controller Card to be able to get up to RAID 5.  The SATA Cables would be connected to the Controller Card and not the backplane.

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Don't forget, with the mod BIOS you can't use the onboard RAID at all. If you don't go with a RAID card, I think this might be a good case for DrivePool or DriveBender.

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Don't forget, with the mod BIOS you can't use the onboard RAID at all. 

 

Oh, actually I hadn't realized this detail at all. This might be a problem. I have never heard about DrivePool and DriveBender either, but at a first quick look on the web it seems like they're a software solution. Which RAID card model would you suggest that could solve this case (5 HDDs to be connected in a unique RAID array)?

 

Is there a way of using the internal additional SATA port at full speed without losing the onboard RAID?

 

Sorry for all this questions, but they're necessary for me to understand if it's worth the price adding just 3TB and then solving loads of new issues ;-)

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DrivePool and DriveBender are software solutions. I have not used them (although I plan to do some specific testing with DrivePool very soon), but forum members who have say they're very good. Joe_Miner, in particular, has done a lot of work with DrivePool.

 

I'm partial to LSI/3ware RAID cards, but they're pretty expensive. Based on the experiences of other forum members, the RocketRaid 2720 seems to be a good, lower-cost option. pcdoc has probably done the most work with these.

 

AFAIK, there is no way to run the internal SATA and the eSATA ports at full speed and retain the ability to use RAID. My own feeling is that this is the main reason HP didn't include the ability to change the RAID mode in the default BIOS. They had a choice to make: retain RAID, or give full speed to the 2 ports - they opted for retaining RAID. That's my feeling anyway.

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You really made my day, thank you! :-) I think I'm going to get more information about the RocketRAID 2720 because it seems cheap and exactly solves my problem. As a last question: would the onboard RAID become completely useless once I've changed the BIOS?

 

I'm sorry for being petulant. If there exists an online or book-like source to learn something - more specific than Wikipedia - about RAID and hardware related to it, I would be happy to study it! ;)

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My understanding is that, once you switch the system to RAID while using the mod BIOS, it becomes unbootable. I didn't try it, since I had the great info from these forums; I believe what Joe_Miner and others have said.

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Coming from a complete RAID novice, I can attest to the fact that the RocketRaid 2720SGL is a good solution.  It was incredibly easy to setup and get running, and was right around $200 (US).  Easy and cheap way to get RAID 5, 6, and even others (I have mine setup in a RAID 5).  Just be aware that it uses SAS connections so buy the correct cable to use with the drives, I believe it is a reverse breakout cable to go from an SAS connection on one end of the cable to 4 SATA connections on the other end, but I may be wrong on that so do a bit of research to confirm.

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