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Server Set Up Advice


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#1 maggy55

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Posted 17 August 2014 - 05:00 PM

Hi,

 

I am setting up a Poweredge 2950 sever for a small company, around 30 people. There are 6 146gb SAS drives installed. I have set up Raid 1 on 3 sets of drives, so I have 3 mirrored drive volumes to work with. I was planning on installing 2008R2 on the first volume and make that my DC and add the HyperV role. I was going to use volume 2 for my virtual server machines and volume 3 for my shared networrk files. Any thoughts or suggestions?

 

Thanks

John



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#2 JohnnyJammer

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Posted 19 August 2014 - 11:00 PM

Nothign wrong with doing it that way mate.



#3 Wand3r3r

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Posted 21 August 2014 - 12:29 PM

I would have suggested a different raid setup.  You left out a very important aspect: Hot Spare

 

I would have made a Raid 1 for the OS

I would have made a Raid 5 for data using three drives.

This would leave you 1 drive that you can configure as a global spare.  This allows this spare to be used immediately for either the mirror set or the raid5 in case either loses a drive

 

The advantage of this is you can schedule the failed drive replacement for off hours instead of having to take the company down during daylight hours to do the replacement


Edited by Wand3r3r, 21 August 2014 - 12:36 PM.


#4 maggy55

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Posted 21 August 2014 - 12:37 PM

Hi,

 

I had thought of using Raid 5 with a hot spare for the data, but keep hearing these horror stories about Raid 5 ?



#5 Wand3r3r

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Posted 21 August 2014 - 12:49 PM

What horror stories? 

 

It is only when you make the entire array raid 5 and then partition for OS and data does adding a drive/space become a nightmare.



#6 technonymous

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Posted 02 September 2014 - 12:10 AM

Rebuilding or increasing capacity of RAID is when it becomes a certifiable nightmare. There is a solution to that. Something to look into http://www.drobo.com/



#7 Techwork

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Posted 20 September 2014 - 03:32 PM

I agree with maggy55 about 1 x RAID 1 for  System and 1 x RAID 5 for data/Virtual machines. Unless you are going for some heavy database setup RAID 5 is fine.

By the way. Hyper-v in Windows server 2012 is awesome :-)


Best regards
 

Thomas
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#8 starrouter

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Posted 07 November 2014 - 10:20 PM

+1 for RAID 5.  I've used a RAID 5 on many servers for 20+ years and never had a reason to complain.  I also see no problem with the way you have already set it up.   Buy one or two compatible used drives for spares to keep handy if needed, they're fairly inexpensive.



#9 Wand3r3r

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Posted 10 November 2014 - 11:23 AM

" Buy one or two compatible used drives for spares to keep handy"

 

That is not how you handle raided systems.  Spare drives need to be in the raid array available for instant failover.



#10 starrouter

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Posted 10 November 2014 - 11:57 AM

" Buy one or two compatible used drives for spares to keep handy"

 

That is not how you handle raided systems.  Spare drives need to be in the raid array available for instant failover.

 

Yes it is.   That is exactly how RAID5 works.  The Poweredge 2950 has hot-swap drives, if one fails, you just unplug the failed drive and plug the spare in with the server running and the new drive starts rebuilding immediately.  There is a RAID 5E and 5EE, some refer to it as "RAID 5 + 1 Hot Spare" which is RAID 5 Enhanced and has a hot spare already running and that's what you're thinking about but those are non-standard RAID configurations.  Nice feature, but usually not necessary if you look at your servers on a daily basis and I don't know for sure but I doubt the Poweredge 2950 does that kind of RAID,

 

Wand3r3r, Posted 21 August 2014 - 10:29 AM

"This would leave you 1 drive that you can configure as a global spare.  This allows this spare to be used immediately for either the mirror set or the raid5 in case either loses a drive"

 

This is also incorrect.  A hot-spare in a 5E or 5EE array will only be used in that array.  You could make the mirror a RAID 1E and have another hot-spare for that array too, but there aren't a lot of older RAID controllers that support these non-standard RAID configurations and I have several PE2950's that won't support that kind of RAID.  One could always buy and install a newer controller though.

 

Wand3r3r, Posted 21 August 2014 - 10:29 AM

"The advantage of this is you can schedule the failed drive replacement for off hours instead of having to take the company down during daylight hours to do the replacement"

 

With a standard RAID 5 on a server with hot-swap drive bays like the PE2950, you don't have to take anything down to replace a failed hard drive.  With the server running, just unlatch the failed drive and slide it out, then slide the new drive in and latch it - that's it.  The new drive will start rebuilding automatically.  That's what hot-swap means, you replace the drives while it's running.  Really no need for an online spare as far as I'm concerned at-least in this scenario.


Edited by starrouter, 10 November 2014 - 03:58 PM.


#11 Wand3r3r

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Posted 10 November 2014 - 05:28 PM

"A hot-spare in a 5E or 5EE array will only be used in that array"

 

What you write starrouter appears to only pertain to that controller not the many different ones I have worked with.  I have configured many a global hot spare in Adaptec and LSI controllers.

 

The scheduling of taking down a server to remove the defective drive and reconfigure the hot spare is based not on a hot swap array.

 

Do understand that your methodology of doing hot swaps without hot spares is going to bite you in the butt one day.  All you need are two drives to fail one after the other during the night and your array is dead and the data only as good as the last backup.  Having at least one hot spare [I usually have two] will give you that margin of error that can make the difference of being live vs being dead.



#12 starrouter

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Posted 10 November 2014 - 08:25 PM

"What you write starrouter appears to only pertain to that controller"

That would apply to that controller and the majority of controllers that were available when the PE2950 was made.  You are right that controllers that allow you a global hot spare are not only available, but now widely available.  My information was out of date.

 

The OP was talking about using an old server with older small hard drives and It sounded like they were wanting to use the hardware that they had and that would be a controller doing plain Raid 1 or Raid 5, and hot-swap drives since the 2950 has those.  They could upgrade the hardware, new controller, bigger hard drives, etc.. but it sounded like they were more interested in configuration options for what they had.

 

An array with a running hot spare is an extra margin of safety for sure.  If their budget allows for a hardware upgrade or if they already have the hardware to do it with then that would be easy to decide.  I have yet to have lost a raid 5 array because of multiple drive failures, although it is a possibility.  I have lost one because of a controller failure.



#13 Wand3r3r

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Posted 12 November 2014 - 11:41 AM

The drive failure issue is related to getting a box of drives from the same manufacturing lot.  I had a raid 0+1 array which had a global hot spare which when a drive failed the hot spare was used.  Before I could get another drive back under warranty I lost another drive [a week from the other] and lost the array.  Fortunately I had good backups.  Lesson was get drives from different lots so their mtbf were different.



#14 JohnnyJammer

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Posted 12 November 2014 - 10:21 PM

The drive failure issue is related to getting a box of drives from the same manufacturing lot.  I had a raid 0+1 array which had a global hot spare which when a drive failed the hot spare was used.  Before I could get another drive back under warranty I lost another drive [a week from the other] and lost the array.  Fortunately I had good backups.  Lesson was get drives from different lots so their mtbf were different.

Dam that would have sucked lol. Always have more than 1 hot spare hey!






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