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Difference between hard drive & additional hard drive?
Hello,
I'd like to know the difference between this 2 devices. And why do we have to choose the additional one once 2 HD have been chosen?
"For the RAID connectivity you have selected you can not use options with the wordsAdditional Hard Drive from 1st or 2nd Hard Drive Modules. Also you must select options with the words Additional Hard Drive from 3rd Hard Drive onwards."
Mathiau
105 Posts
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September 28th, 2008 16:00
WHat raid selection did you choose?
you have to choose harddrive that correspond to the raid card / configuration you choose, such as hot swap or not hot swap et cetera.
gart_em
22 Posts
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September 28th, 2008 19:00
I chose SAS 6iR RAID controller card. Anyway for the other configurations, you still have the choice between HD and additional HD, that's the difference I would like to know a little bit :) Why additional? The 3rd and 4th HD are still intern, aren't they?
snapohead
1.2K Posts
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September 29th, 2008 04:00
Your post is rather vague. I'm guessing your looking on the Dell website at purchasing a system, and you're choosing RAID levels? I can only assume you've selected RAID 1 as the RAID level, hence, any HDDs will be additional as a RAID 1 can only use 2 HDDs.
gart_em
22 Posts
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September 29th, 2008 06:00
Sorry, I am going to try to be a little more precise. I would like to purchase a T300 server. 4 disks are available and I am going to set 2 RAIDs 1 with a SAS 6iR internal RAID controller in PCI-Express.
The compatibility instructions specifies "For the RAID connectivity you have selected you can not use options with the wordsAdditional Hard Drive from 1st or 2nd Hard Drive Modules. Also you must select options with the words Additional Hard Drive from 3rd Hard Drive onwards."
So my questions are:
- Why should we have to select "additional", what does it correspond to? In a RAID 1, the additional HD corresponds to the disk which aim is mirroring? (that's why I have to select 2 hard drives and 2 complement additional HD? Are they different?)
- Why do we have to respect an order in the HD selection? What is the logic in it?
Thanks a lot in advance for your explanations.
compaqfan
13 Posts
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September 30th, 2008 19:00
Still not following you but I'll try to decipher.
For clarification, the SAS6ir is not a PCIe card, it's an internal card that plugs into the system board (or it may be just a key now) that allows you to run RAID. From the options on the web page there is no way to have (2) RAID-1 sets. You can only pick 2 drives with RAID-1. So, if you still want 4 drives you have 2 options, pick RAID-0 or no RAID. After you get the system, with any luck the controller will allow you to build two RAID-1 sets.
I'd call Dell to verify first or try to find the SAS6ir documentation online to confirm. Also, as someone mentioned above make sure you pick the "hot-plug" or "cage" options correctly.
snapohead
1.2K Posts
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September 30th, 2008 23:00
Anything exceeding the two disks will be "additional", as a RAID 1 only requires two disks. In real terms, whether the word "additional" is there or not is entirely irrelevant. There is no differrence between the initial two disks, and the "additional" disks (provided, of course, that all four disks are of the same spec).
The wording on the website may not be the best for those that don't understand this.
The logic is simply that, as i've said above, anything exceeding the two disks for a RAID 1 is additonal, as they cannot be used in a RAID 1 array.
gart_em
22 Posts
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October 1st, 2008 12:00
Compaqfan: - are you sure the SAS 6iR RAID controller can't be in PCIe? Because I've made this choice on the website: "SAS 6iR internal RAID Controller, PCI-Express" - Besides, from the options on the web page there is a way to have (2) RAID-1 sets : "C17- Add-in SAS6iR controller, 4 hot-plug Hard Drives - RAID 1/RAID 1". Don't you have access to this option? Anyway thanks for your advices :)
snapohead: The wording on the website is indeed not really the best, especially since the choice of RAID1-RAID1is taken in account (so if we choose RAID1-RAID1, the HD are no more additional...). In brief thanks a lot for your latest explanations that's exactly what I wanted to know!
Still I have a slight problem : As I said above, I've chosen a RAID 1/RAID 1 configuration: -1st RAID 1 = 2*80GB SATA HD 7,200 rpm -2nd RAID1 = 2*160GB SATA Additional HD 7,200 rpm. The configurator specifies that "The RAID connectivity you have selected requires exactly 4 hard drives of the same size and speed or you can have 2 pairs of 2 of the same size and speed". However with the configuration I have done above, I have still an error message :
" For the RAID connectivity you have selected you can not use options with the wordsAdditional Hard Drive from 1st or 2nd Hard Drive Modules. Also you must select options with the words Additional Hard Drive from 3rd Hard Drive onwards."
The error message disappears if I choose the same 4 HD but as it is specified, I should have 2 pairs of 2 of the same size... Isn't it contradictory? How should I configure my HD so that I do not have errors any more?
Mathiau
105 Posts
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October 5th, 2008 15:00
gart_em
22 Posts
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October 6th, 2008 11:00
gart_em
22 Posts
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October 6th, 2008 13:00
snapohead
1.2K Posts
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October 12th, 2008 22:00
Your comment is incorrect.
Raid 1, by definition, can only have two drives. After that, it becomes 1+0 or 0+1.
And you cannot have less than 3 drives in a RAID 5, 4 in a RAID 6, ETC...