RAID10 Expansion/Reconstruction

JaredBusch

Honestly I had no idea that the PERC allowed expansion.

Obsolesce

@jaredbusch said in RAID10 Expansion/Reconstruction:

Honestly I had no idea that the PERC allowed expansion.

Yeah, more specifically, on-line expansion. I should have specified that above.

This is being done through Dell's OMSA.

scottalanmiller

@jaredbusch said in RAID10 Expansion/Reconstruction:

Honestly I had no idea that the PERC allowed expansion.

Same here.

scottalanmiller

@tim_g said in RAID10 Expansion/Reconstruction:

@jaredbusch said in RAID10 Expansion/Reconstruction:

Honestly I had no idea that the PERC allowed expansion.

Yeah, more specifically, on-line expansion. I should have specified that above.

This is being done through Dell's OMSA.

Keep in mind that mirrored RAID expansion is not reconstruction. Very different things.

Only Parity RAID has a reconstruction/expansion mixed operation.

For mirrored RAID to grow, it has to move ALL data off of the original array, rebuild it, and put it all back. It's an insanely enormous operation and there is little operating space for the system to do that. It's actually a pretty amazing technical feat. I can come up with ways to do it, but they are incredibly intensive and require special hardware support. Doable, but there is a reason it is slow.

Obsolesce

@scottalanmiller said in RAID10 Expansion/Reconstruction:

@tim_g said in RAID10 Expansion/Reconstruction:

@jaredbusch said in RAID10 Expansion/Reconstruction:

Honestly I had no idea that the PERC allowed expansion.

Yeah, more specifically, on-line expansion. I should have specified that above.

This is being done through Dell's OMSA.

Keep in mind that mirrored RAID expansion is not reconstruction. Very different things.

Only Parity RAID has a reconstruction/expansion mixed operation.

For mirrored RAID to grow, it has to move ALL data off of the original array, rebuild it, and put it all back. It's an insanely enormous operation and there is little operating space for the system to do that. It's actually a pretty amazing technical feat. I can come up with ways to do it, but they are incredibly intensive and require special hardware support. Doable, but there is a reason it is slow.

I see, that makes sense.

I keep using "reconstruction" because that's the "state" of the virtual disk:

scottalanmiller

@tim_g said in RAID10 Expansion/Reconstruction:

@scottalanmiller said in RAID10 Expansion/Reconstruction:

@tim_g said in RAID10 Expansion/Reconstruction:

@jaredbusch said in RAID10 Expansion/Reconstruction:

Honestly I had no idea that the PERC allowed expansion.

Yeah, more specifically, on-line expansion. I should have specified that above.

This is being done through Dell's OMSA.

Keep in mind that mirrored RAID expansion is not reconstruction. Very different things.

Only Parity RAID has a reconstruction/expansion mixed operation.

For mirrored RAID to grow, it has to move ALL data off of the original array, rebuild it, and put it all back. It's an insanely enormous operation and there is little operating space for the system to do that. It's actually a pretty amazing technical feat. I can come up with ways to do it, but they are incredibly intensive and require special hardware support. Doable, but there is a reason it is slow.

I see, that makes sense.

I keep using "reconstruction" because that's the "state" of the virtual disk:

Right, well it IS reconstructing. But the term means something different than it does with RAID 5 or 6. With RAID F reconstruction is literally "we told the array it was broken, that the parity wasn't parity but actual data and told it to restore parity to the new drive." Which is just a fancy way to say "We downgraded this RAID 6 to a RAID 5, added a disk and told it to recover."

With RAID 10, it's "we are reconstructing the data from scratch in a way that is totally unlike any RAID operation."

So one is a reconstruction of your RAID array, the other is inherent RAID reconstruction.