Server RAID environment

Abraham Deutsch
Abraham Deutsch used Ask the Experts™
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My server is hardware based RAID 1 configured
I want to add a hard drive so I can split the operating system and date on two physical hard drives which in general increases performance when thy are not on the same physical Drive. Is this possible in a RAID 1 environment? (having the server writing to two drives  and on for mirror? I notice when I configure a server at dell online if I select RAID 1 it will not allow to add more than 2 drives)
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FOXActive Directory/Exchange Engineer
Top Expert 2015

Commented:
If you want to add more than 2 drives I would go with Raid 5 with a hot spare.  Most reliable and efficient

http://www.thegeekstuff.com/2010/08/raid-levels-tutorial/
PowerEdgeTechIT Consultant
Top Expert 2010

Commented:
If you are looking at Dell, yes, this is possible ... you can have multiple arrays on the controller/server. A single RAID 1 can only have two drives, so you would have two RAID 1's.
PowerEdgeTechIT Consultant
Top Expert 2010

Commented:
Don't use RAID 5.
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Abraham DeutschIT professional
Top Expert 2016

Author

Commented:
I agree with you PowerEdgeTech As I don’t see a need for raid 5, but Dell has no option of 2 raid 1. I see there I aworkaround also I see a option raid 1/unconfigured raid, which I am not sure what it stands for.  I would say  RAID 0+1 is what I am looking for but I don’t see such a option
Most Valuable Expert 2015

Commented:
Just add two further disks and make a separate RAID 1 array for those.
IT Consultant
Top Expert 2010
Commented:
All Dell controllers can absolutely support multiple RAID 1 arrays. If you can't select RAID 1 + RAID 1 online, it is just a limitation of the online configurator.

RAID 10 is a good option, but you can't reconfigure an existing RAID 1 to be a RAID 10. You would have to do a backup/restore. So, is this for a new machine that you don't have yet? If so, then you can configure it however you want once you get it - just order it with the number of disks you want. RAID 10 a RAID 0 across RAID 1 pairs.
Leroy LuffHead of IT & DIgital

Commented:
I agree with PowerEdge - Go Raid 10 - you would need atleast 4 hardrives.
Most Valuable Expert 2015
Commented:
With RAID 10 the user doesn't get what he want's, two RAID arrays, one for the OS, the other for data. But with 2 RAID 1 arrays he would get that.
Leroy LuffHead of IT & DIgital

Commented:
Rindi - Its exactly what he wants.

He is looking for 2 raid 1 arrays to split OS and data for performance.

Raid 10 gives much better redundancy and performance than 2 Raid 1 sets. After the array is created he can just partition the volume for OS and Data,
Abraham DeutschIT professional
Top Expert 2016

Author

Commented:
I'm in the process of putting together a new server
PowerEdgeTechIT Consultant
Top Expert 2010

Commented:
If you are in the process of building a new server, then know you can do whatever you want regardless of the options you are presented with the online configurator.
Abraham DeutschIT professional
Top Expert 2016

Author

Commented:
Is RAID 10 accomplishing the purpose? With RAID 10 the operating system and date work on the same drives (longingly) even if its fiscal two drives, versus two Raid 1 the two hard drives work independently
Also RAID 10 has a down side. If one of the hard drives fail, the other is worthless as it only has half of the information versus two Raid 1 which only the defected one needs to be replaced.
PowerEdgeTechIT Consultant
Top Expert 2010
Commented:
Also RAID 10 has a down side. If one of the hard drives fail, the other is worthless as it only has half of the information versus two Raid 1 which only the defected one needs to be replaced.
No, this isn't how RAID 10 works. RAID 10 is essentially a RAID 0 striped across disk spans, but each span of the RAID 0 is a redundant mirror (RAID 1). (RAID 60 is a RAID 0 across RAID 6 sets.) If a disk fails in a RAID 10, only one of the spans becomes degraded (but the array is still online). You can lose ONE disk per span. If you lose a second disk from the same span, the array is offline.

RAID 10 has potentially better speeds than a single RAID 1, as the data can be read from (or written to) two (or more) disks (spans) simultaneously. Separating reads/writes between disk sets (separate RAID 1's) will certainly gain you some performance, depending on the nature of the data being exchanged. If you were to benchmark the two, I suspect there would be very little difference between the two ... again, depending entirely on the actual use and configuration.

Any Dell controller will do any of this that you want, but I would strongly recommend you not consider any controller except the H7x0 controllers.
Abraham DeutschIT professional
Top Expert 2016

Author

Commented:
according to dall recommendation a 7xx controller is only needed with a RAID 5
PowerEdgeTechIT Consultant
Top Expert 2010

Commented:
As long as you are considering RAID, I would recommend the H7x0 controller regardless of your desired configuration.

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