Question about weather or not I should enable write-through mode on a RAID1 SSD array
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I'm building out a new server and I've selected the H730P RAID controller which has 2GB NV flash backed cache. My array will be a RAID1 of two 3.8TB Samsung PM1633a SSD drives.
Looking at the PM1633a whitesheet, I see that it actually has power loss protection. Doing a bit of googling, I have found some info that suggests that performance could suffer on the array if using a controller that has write back cache enabled, but I'm not too clear on the specifics.
It seems like there are two pieces of hardware which offer the same type of function and I'm not sure if this is ok or not or if I should even worry about it. Should I trust the power loss feature on the SSD? Should I leave write-through mode off on the controller? I did see that the H730P boasts, "Increases IOPS performance with Solid State Drives (SSDs) utilizing FastPath".
If I should disable the write-back cache on the H730P and rely on the PM1633a's power loss protection only, then I may as well just purchase the H330 instead, as it does not have write back cache.
Sorry if this is a basic storage question.. I'm still learnings (SSDs) utilizing
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@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
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@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
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@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
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I'd enable write-back. You will increase the life of the drives and increase performance in many situations. It's a lot faster than the SSDs as well.
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@obsolesce said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
I'd enable write-back. You will increase the life of the drives and increase performance in many situations. It's a lot faster than the SSDs as well.
yeah I mean, if it can't hurt anything, I will just keep the H730P or H740P. No big deal. I just didn't want to have some kind of performance issue crop up.
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@obsolesce said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
I'd enable write-back. You will increase the life of the drives and increase performance in many situations. It's a lot faster than the SSDs as well.
This is, I think, the bigger deal. The 8GB shared cache is way more useful than the 4GB redundant caches, and gives the controller time to properly queue writes, eliminate unnecessary writes, and reduce wear on the SSDs.
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@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
Of course they were, they're job is to sell you thing, or more expensive things, than you really need.
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@travisdh1 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
Of course they were, they're job is to sell you thing, or more expensive things, than you really need.
That's kind of what I was thinking.. though I have had many times where vendors like Dell just don't do that. Sure they want to sell you stuff but it's not good to constantly take advantage of people either as it will catch up to you one way or another. Case and point, I over-spec'd a system a while back and my Dell VAR suggested I go with part X because it was just as good as part Y only a lot cheaper.
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What kind of drives did you settle on?
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@travisdh1 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
Of course they were, they're job is to sell you thing, or more expensive things, than you really need.
True, but in this case it was their tech department, not sales. But in any case, SSD technology moves fast so a lot has happened in the last three, four years.
Dell (and others) are also pretty slow in adopting new technology and it takes a while for new drives to show up in their line up so I guess the drive Dell had back then were already old.
That's why I like Supermicro - they keep up with new tech and you can mix and match to your heart's content.
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@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@travisdh1 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
Of course they were, they're job is to sell you thing, or more expensive things, than you really need.
That's kind of what I was thinking.. though I have had many times where vendors like Dell just don't do that. Sure they want to sell you stuff but it's not good to constantly take advantage of people either as it will catch up to you one way or another. Case and point, I over-spec'd a system a while back and my Dell VAR suggested I go with part X because it was just as good as part Y only a lot cheaper.
A VAR might just want to do a good job. But it's more complex than people say. It's never about "more expensive", but it is generally about better margins. Which are impossible for end users to determine.
The cheaper hard drives might have had equal or better margins than the expensive ones. We say "expensive", but that's dumbing down something that doesn't need dumbing down, and implies that we can easily tell when we are being led for profits based on the resulting price, which is incorrect.
There is every reason to believe your VAR was just doing a good job for you. But the result of a lower price doesn't tell us in any way if they or Dell themselves did something purely in your interest, or also in theirs. And there is always the possibility that the more expensive drives offered something that would have been beneficial to you.
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@scottalanmiller said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@travisdh1 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@pete-s said in Question about weather or not I should enable write-through mode on a RAID1 SSD array:
@dave247 All enterprise SSDs have power protection caps so that is an expected feature.
If the raid controller cache makes an improvement or not depends on the workload and the size of the cache.
I think the 3.84TB drives have 4GB cache internally. That's large compared to the RAID controllers cache. What do Dell recommend?
I haven't asked Dell what they recommend. The H730P has 2GB and the H740P has 8GB though.
Give them a call. A little more than 3 years ago I spec'ed a computer with 4 SATA SSDs in two RAID1 arrays and I remember that they were adamant that I get the H730P controller. Machine was an R630.
Of course they were, they're job is to sell you thing, or more expensive things, than you really need.
That's kind of what I was thinking.. though I have had many times where vendors like Dell just don't do that. Sure they want to sell you stuff but it's not good to constantly take advantage of people either as it will catch up to you one way or another. Case and point, I over-spec'd a system a while back and my Dell VAR suggested I go with part X because it was just as good as part Y only a lot cheaper.
A VAR might just want to do a good job. But it's more complex than people say. It's never about "more expensive", but it is generally about better margins. Which are impossible for end users to determine.
The cheaper hard drives might have had equal or better margins than the expensive ones. We say "expensive", but that's dumbing down something that doesn't need dumbing down, and implies that we can easily tell when we are being led for profits based on the resulting price, which is incorrect.
There is every reason to believe your VAR was just doing a good job for you. But the result of a lower price doesn't tell us in any way if they or Dell themselves did something purely in your interest, or also in theirs. And there is always the possibility that the more expensive drives offered something that would have been beneficial to you.
Yeah I see what your saying. Actually the parts in my example were the new Intel processors. I selected a Xeon Gold and he suggested I go with Silver as they also perform well and just because they are "silver" doesn't mean they are a less better version of the Gold. And in actuality, the reason I chose Gold was because I was trying to get more Ghz but I understand that's not all there is to a CPU. It was my first pass at a build.
