How to Over Provision RAID 0?

[G73S]

So I created a RAID 0 Strip Array with a 128K data cluster as my Alienware mothebroard suggested that it is the best size

anyway, I created the RAID array in full size which was like 1.8 TB usable space

I partitioned the fist partition where my OS + Games will be installed to 300 GB

Then I partitioned the D partition to 80% of the total 1.8 TB size of the RAID array

Did I do it right or is there a better way of doing this?

I chose 20% OP as Samsung Magician usually suggests 10% OP for a drive, so combining 2 drives I OPed by 20%

But how in the world does the SSDs know which where is the gargbage collection since the unpartitioned space is in a RAID array?

please advice

 

[G73S]

anyone?

 

[aigomorla]

can I ask why u decided to partition SSD's in R0?

why not just keep it as one big drive?

 

[mindbomb]

can I ask why u decided to partition SSD's in R0?

why not just keep it as one big drive?

I've heard of people doing this because their raid controller doesn't support trim

 

[aigomorla]

I've heard of people doing this because their raid controller doesn't support trim

I don't think it would support trim anyhow.

he has 2 ssd's in R0 and then setup a partition on that R0 array.

The only thing I can think of is if he does a frequent OS reinstall in which he doesn't want to lose the contents of a partition.

However with SSD's I was always told to wipe the entire contents of the SSD b4 u reinstall.

By setting up a partition like that, he can never wipe the complete SSD.

 

[Unoid]

I've read that smaller stripe sizes are ideal for SSD

 

[Cerb]

I've read that smaller stripe sizes are ideal for SSD

It really shouldn't matter. In a cacheless RAID, especially, the stripe size should have nearly zero impact on non-synthetic performance. I would just use the Intel or LSI default, unless performance was clearly poor with defaults (also, Intel's is the only FakeRAID I'd bother with, and LSI the only hardware RAID 🙂).

 

[G73S]

can I ask why u decided to partition SSD's in R0?

why not just keep it as one big drive?

because I liked to have my docs, pics, videos, music, etc on a separate partition, so when i backup an image of C: (the OS), and restore it, I don't lose all my personal data

 

[G73S]

I don't think it would support trim anyhow.

he has 2 ssd's in R0 and then setup a partition on that R0 array.

The only thing I can think of is if he does a frequent OS reinstall in which he doesn't want to lose the contents of a partition.

However with SSD's I was always told to wipe the entire contents of the SSD b4 u reinstall.

By setting up a partition like that, he can never wipe the complete SSD.

exactly, you got it 100% right

 

[G73S]

I've heard of people doing this because their raid controller doesn't support trim

no TRIM is supported if it's on RAID 0, not any other RAID mode though

TRIM Check test results:

Mind you, TRIM only starts working in a RAID 0 environment AFTER you have installed the IRST driver

 

[G73S]

I've read that smaller stripe sizes are ideal for SSD

I just choce what the Alienware motherboard suggested, for RAID 0 = 128K size

 

[G73S]

not one reply about how to OP a RAID 0 though

what I did was, create a RAID 0 array with the max size of both my drives, then in Windows, I partitioned C: to 300 GB, and D to 1.34 TB and left 20% unpratitioned space

is this right? or is OP done initially when creating the RAID array that I have to make it 20% less? that's my confusion

 

[imagoon]

I've heard of people doing this because their raid controller doesn't support trim

It has a minimal effect anyway. Modern drives have spare areas that are typically 7% of flash. So an example Samsung 830 / 840 256GB drive would have just under 18GB of spare blank block per drive. In RAID 0 this becomes 36GB of spare blank blocks. You would need to write 36GB at the full speed the drives take to have a chance to hit an uncleared block. This is highly irregular in most cases for home users. Garbage collection will also regularly clear the spare area as well.

If you want to under provision properly, you need to use the SSD tools otherwise the GC never knows to clean those areas and if TRIM commands are ignored or lost (from shutting the drive off for example) you will eventually land at 7% free blocks anyway.

 

[Chapbass]

not one reply about how to OP a RAID 0 though

what I did was, create a RAID 0 array with the max size of both my drives, then in Windows, I partitioned C: to 300 GB, and D to 1.34 TB and left 20% unpratitioned space

is this right? or is OP done initially when creating the RAID array that I have to make it 20% less? that's my confusion

I would imagine that when creating the raid you want to make it 20% less, but I'm honestly not sure.

 

[Cerb]

If you want to under provision properly, you need to use the SSD tools otherwise the GC never knows to clean those areas and if TRIM commands are ignored or lost (from shutting the drive off for example) you will eventually land at 7% free blocks anyway.

If done via partitioning from a fresh/SE state, or TRIM is run before putting it to use (such as making and removing partitions in disk manager under 7+), complete with some idle on time after that, it should be fine (the LBAs only need TRIM once).

 

[imagoon]

If done via partitioning from a fresh/SE state, or TRIM is run before putting it to use (such as making and removing partitions in disk manager under 7+), complete with some idle on time after that, it should be fine (the LBAs only need TRIM once).

Depends. If the blocks are not TRIMed for any reason or the TRIM command is lost because it hasn't been processed by GC before the table is lost (power loss, drive doesn't have time to process so the table is dropped etc) then that percentage will slow drop until it hits the ~7% original provisioning.