Server with multiple backplane / Drive Configuration
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I have a server that will have 6 SSD drives (RAID5) and 4 HDD's (RAID 10)
There are two backplanes with a capacity of 8 drives each.
Does it matter if drives are split between backplanes?
For example:
Backplane 1: 6 SSD's and 2 HDD's
Backplane 2: 2 HDD'sOr is it better to keep all like drives (or drives in same array) on the same backplane?
Example:
Backplane 1: 6 SSD's and 2 empty spots
Backplane 2: 4 HDD's with 4 empty spotsI'm thinking it doesn't matter as they are all on the same RAID card, but wanted to verify.
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As you stated- if the drives are all on the same RAID card, the backplane should allow for almost any pairing..
In theory.
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My vote would be to follow your example of keeping each array together on the backplane, not sure if it's going to make a difference but that's my gut.
You're inevitably going to get a question / inquisition on why R5 on the 6 SSDs so.... counting down .... 3..... 2...... 1.....
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@notverypunny said in Server with multiple backplane / Drive Configuration:
My vote would be to follow your example of keeping each array together on the backplane, not sure if it's going to make a difference but that's my gut.
You're inevitably going to get a question / inquisition on why R5 on the 6 SSDs so.... counting down .... 3..... 2...... 1.....
Sure, my answer would be why not RAID 5?
(RAID 5 on spinning drives is a bad idea, but since SSD's are completely different RAID 5 on an SSD array is just fine.) -
@CCWTech It depends on the backplanes. There are different types.
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@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech It depends on the backplanes. There are different types.
Ok, Can you explain more please?
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Generally you want to use the backplanes strategically. Put all of one RAID on each backplane OR split the RAID 10 with half of each RAID 1 on one backplane and half on the other to protect against backplane failure.
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@CCWTech said in Server with multiple backplane / Drive Configuration:
I have a server that will have 6 SSD drives (RAID5) and 4 HDD's (RAID 10)
There are two backplanes with a capacity of 8 drives each.
Does it matter if drives are split between backplanes?
For example:
Backplane 1: 6 SSD's and 2 HDD's
Backplane 2: 2 HDD'sOr is it better to keep all like drives (or drives in same array) on the same backplane?
Example:
Backplane 1: 6 SSD's and 2 empty spots
Backplane 2: 4 HDD's with 4 empty spotsI'm thinking it doesn't matter as they are all on the same RAID card, but wanted to verify.
If the RAID card is reading the drives correctly as far as slot ID across both backplanes then things should be okay.
You should be able to run through the server's management interface and blink each drive to verify.
We tend to split-up high bandwidth/IOPS drives across cables.
In this case, we'd put half of the SSDs on one backplane and half on the other and set up the RAID array that way. This gives us a lot more bandwidth to play with.
HDDs don't really care so much about that.
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@CCWTech said in Server with multiple backplane / Drive Configuration:
@notverypunny said in Server with multiple backplane / Drive Configuration:
My vote would be to follow your example of keeping each array together on the backplane, not sure if it's going to make a difference but that's my gut.
You're inevitably going to get a question / inquisition on why R5 on the 6 SSDs so.... counting down .... 3..... 2...... 1.....
Sure, my answer would be why not RAID 5?
(RAID 5 on spinning drives is a bad idea, but since SSD's are completely different RAID 5 on an SSD array is just fine.)Better answer - because math.
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@PhlipElder said in Server with multiple backplane / Drive Configuration:
We tend to split-up high bandwidth/IOPS drives across cables.
In this case, we'd put half of the SSDs on one backplane and half on the other and set up the RAID array that way. This gives us a lot more bandwidth to play with.
So you're saying the backplane cable is a bottleneck?
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@Dashrender said in Server with multiple backplane / Drive Configuration:
@CCWTech said in Server with multiple backplane / Drive Configuration:
@notverypunny said in Server with multiple backplane / Drive Configuration:
My vote would be to follow your example of keeping each array together on the backplane, not sure if it's going to make a difference but that's my gut.
You're inevitably going to get a question / inquisition on why R5 on the 6 SSDs so.... counting down .... 3..... 2...... 1.....
Sure, my answer would be why not RAID 5?
(RAID 5 on spinning drives is a bad idea, but since SSD's are completely different RAID 5 on an SSD array is just fine.)Better answer - because math.
Ha. . . that is what it really comes down too. The math just doesn't show any risk of URE when using SSDs in an OBR5. And since generally speaking SSDs don't limp along but instead just die when they do go, it's much more apparent to replace any failed equipment.
The the recovery times are so much faster with SSDs. Still have the impact of rebuilding the array on the drives, but you can't get around that.
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@Dashrender said in Server with multiple backplane / Drive Configuration:
@PhlipElder said in Server with multiple backplane / Drive Configuration:
We tend to split-up high bandwidth/IOPS drives across cables.
In this case, we'd put half of the SSDs on one backplane and half on the other and set up the RAID array that way. This gives us a lot more bandwidth to play with.
So you're saying the backplane cable is a bottleneck?
Each cable has four SAS/SATA paths in it. So yes, with SSDs it is possible to saturate a single cable set.
A single 6Gbps SAS cable saturates around 377K IOPS. A single 12Gbps cable saturates around 750K IOPS. At least, that's what's happened in our own in-house storage thrashing tests.
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@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech It depends on the backplanes. There are different types.
Ok, Can you explain more please?
Well, the backplanes can be wired straight, meaning you have literally 1 SAS port for every bay. And the RAID card has to have support for 8 SAS ports per backplane (two cables).
Or the backplanes can be wired with integrated SAS expanders. Then you usually have 4 SAS ports from the RAID card to the SAS expander in one cable.
Then there is also the possibility that you have dual SAS expanders on the backplanes for using fail-over configuration.
The backplanes can also internally be wired in a daisy-chain configuration which means that backplane number two isn't fed from the RAID card but from the first backplane and only the first backplane is hooked up to the RAID card.
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Better answer - because math.
LOL, true.
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What server/model is it?
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@Pete-S said in Server with multiple backplane / Drive Configuration:
What server/model is it?
HP ML350 Gen 10
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@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
What server/model is it?
HP ML350 Gen 10
https://techlibrary.hpe.com/docs/iss/ML350_Gen10/setup_install/
OK, looks like there are many storage options on that machine and many different raid controller options as well.
But, there are no SAS expanders on the backplanes. Backplanes are straight "dumb" wiring so to speak. HPE has an additional SAS expander card that have to be installed if you're using that.
So if you have 16 drive bays I assume 8x2.5" drive bays per "box". You then probably have it paired with the P816i-a controller in which case you have each drive bay directly wired to one SAS port from the controller.
So it makes no performance difference how you install the drives. I would however put the SSDs in one box (one backplane) and the HDDs in the other - just to make it less confusing and less of chance to pull the wrong drive when something fails.
I don't understand why you would use 2.5" HDDs at all though but that is another matter. The server can also be configured with one 8x2.5" and one 4x3.5" bay which would be my preference.
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@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
What server/model is it?
HP ML350 Gen 10
https://techlibrary.hpe.com/docs/iss/ML350_Gen10/setup_install/
OK, looks like there are many storage options on that machine and many different raid controller options as well.
But, there are no SAS expanders on the backplanes. Backplanes are straight "dumb" wiring so to speak. HPE has an additional SAS expander card that have to be installed if you're using that.
So if you have 16 drive bays I assume 8x2.5" drive bays per "box". You then probably have it paired with the P816i-a controller in which case you have each drive bay directly wired to one SAS port from the controller.
So it makes no performance difference how you install the drives. I would however put the SSDs in one box (one backplane) and the HDDs in the other - just to make it less confusing and less of chance to pull the wrong drive when something fails.
I don't understand why you would use 2.5" HDDs at all though but that is another matter. The server can also be configured with one 8x2.5" and one 4x3.5" bay which would be my preference.
Yes, it is the HP SAS expander card I'm using.
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@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
What server/model is it?
HP ML350 Gen 10
https://techlibrary.hpe.com/docs/iss/ML350_Gen10/setup_install/
OK, looks like there are many storage options on that machine and many different raid controller options as well.
But, there are no SAS expanders on the backplanes. Backplanes are straight "dumb" wiring so to speak. HPE has an additional SAS expander card that have to be installed if you're using that.
So if you have 16 drive bays I assume 8x2.5" drive bays per "box". You then probably have it paired with the P816i-a controller in which case you have each drive bay directly wired to one SAS port from the controller.
So it makes no performance difference how you install the drives. I would however put the SSDs in one box (one backplane) and the HDDs in the other - just to make it less confusing and less of chance to pull the wrong drive when something fails.
I don't understand why you would use 2.5" HDDs at all though but that is another matter. The server can also be configured with one 8x2.5" and one 4x3.5" bay which would be my preference.
Yes, it is the HP SAS expander card I'm using.
Since the backplanes in that server doesn't do anything, it makes no difference in what bays you put the drives. Not from a performance perspective and not from a redundancy perspective.
From the SAS expander to the backplane to the drive is electrically the same as just having a straight cable. So there is nothing that can fail - unless you physically abuse it.
The backplane does have some electronic components on it though but that is for driving the LEDs in the drive bays.
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@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
@CCWTech said in Server with multiple backplane / Drive Configuration:
@Pete-S said in Server with multiple backplane / Drive Configuration:
What server/model is it?
HP ML350 Gen 10
https://techlibrary.hpe.com/docs/iss/ML350_Gen10/setup_install/
OK, looks like there are many storage options on that machine and many different raid controller options as well.
But, there are no SAS expanders on the backplanes. Backplanes are straight "dumb" wiring so to speak. HPE has an additional SAS expander card that have to be installed if you're using that.
So if you have 16 drive bays I assume 8x2.5" drive bays per "box". You then probably have it paired with the P816i-a controller in which case you have each drive bay directly wired to one SAS port from the controller.
So it makes no performance difference how you install the drives. I would however put the SSDs in one box (one backplane) and the HDDs in the other - just to make it less confusing and less of chance to pull the wrong drive when something fails.
I don't understand why you would use 2.5" HDDs at all though but that is another matter. The server can also be configured with one 8x2.5" and one 4x3.5" bay which would be my preference.
Yes, it is the HP SAS expander card I'm using.
Since the backplanes in that server doesn't do anything, it makes no difference in what bays you put the drives. Not from a performance perspective and not from a redundancy perspective.
From the SAS expander to the backplane to the drive is electrically the same as just having a straight cable. So there is nothing that can fail - unless you physically abuse it.
The backplane does have some electronic components on it though but that is for driving the LEDs in the drive bays.
Awesome thank you everyone!
