Swapping hdd's for SSD's 7400

[3parnewb]

Hi guys,

I'm managing a 3par 7400 quad controller with 6 enclosures. The system has a 96 disk license and is willed up with 96 sas hdd's.

Now I've purchased 8 4TB SSD's for the 7000 series. What is the best way to swap the HDD's for the SSD's? And what would be the best placement in terms of enclosure? I would think that putting them in the main chassis would be the best in terms of bandwidth.. But I don't know if this is the 3par way

Thanks in advance!

[MammaGutt]

Hi guys,

I'm managing a 3par 7400 quad controller with 6 enclosures. The system has a 96 disk license and is willed up with 96 sas hdd's.

Now I've purchased 8 4TB SSD's for the 7000 series. What is the best way to swap the HDD's for the SSD's? And what would be the best placement in terms of enclosure? I would think that putting them in the main chassis would be the best in terms of bandwidth.. But I don't know if this is the 3par way

Thanks in advance!

All cages have the same bandwidth to the nodes.

However you have few things you need to figure out.

What are you planning on using the SSD for? The minimum supported number of drives for a tier is 6 per node pair. With 8 drives you get 4 per node pair and you can only use it for Adaptive Flash Cache (which in most use cases doesn’t help alot) and you’re limited on size on a 7400.

You can’t put all 8 drives behind one node pair because all nodes are active and handling IO.

Now, if you’re running 3.2.2 you have express layout, so you _could_ technically do 4 drives behind each node pair and run R5 (3+1). It was never supported by HPE… I have no idea if that was for a technical reason or simply avoiding confusion with different minimums on different OS codes.

Either way, ensure drives are installed in pair (ie slot 0+1, 2+3, 4+5, 6+7 etc should always have equal drives).

[3parnewb]

I see. I have 10 drives in total because I bought 2 extra spares. The drives will be used to host database volumes. Not planning to use the AFC feature.

Maybe it has to do with the CPU not being able to calculate flash parity? I fist wanted to make a raid1 over 8 drives as this would already give me enough space to work with. But if you have another recommendation I'm all ear

Running 3.2.2.709 (MU6)+P96,P99

[MammaGutt]

I see. I have 10 drives in total because I bought 2 extra spares. The drives will be used to host database volumes. Not planning to use the AFC feature.

Maybe it has to do with the CPU not being able to calculate flash parity? I fist wanted to make a raid1 over 8 drives as this would already give me enough space to work with. But if you have another recommendation I'm all ear

Running 3.2.2.709 (MU6)+P96,P99

Yeah, 10 drives would be a bigger problem as 5 drives per node pair would be bad.

So I guess the questions is where you want to go with this. As you're running a very old patch level for the 3PAR (I'm thinking last patch seems to be late 2016/early 2017) I'm guessing you don't have a support contract. If you don't have a support contract you probably don't care that much about what is supported on the system and what has been tested as you either way have no where to complain if there are issues.

As for CPU not being able to calculate parity that would be true for pre-3.2.2 versions as 8 drives on 4 node system would give you only 2 drives per node and you can't do much parity with that With express layout the drives are more shared between the nodes in a pair so all nodes have access to 4 drives and should be able to calculate parity without issues.
(Btw, it is the 3PAR ASIC and not CPU doing the ASIC calculations )

[3parnewb]

Yes the last update was done in 2018 as far as I know. The system has no support contract anymore. And I did not find a way to update it Or maybe if you know a way I would really like to know.

So you are saying with the 8 drives I can create 2 x 4 drive R5? That would be fine too and I keep the 2 spares.

[MammaGutt]

So you are saying with the 8 drives I can create 2 x 4 drive R5? That would be fine too and I keep the 2 spares.

I'm saying I don't see a reason why it wouldn't work. But the number of SSDs installed does not reach the minimum supported per tier per node pair.

[3parnewb]

Gotya, I'll check if I can get two more.

So what would be the right way to swap them with the HDD's? And you said I need to divide all the SSD's over all the cages? Sorry I'm not a pro in 3par as you can see

[MammaGutt]

Gotya, I'll check if I can get two more.

So what would be the right way to swap them with the HDD's? And you said I need to divide all the SSD's over all the cages? Sorry I'm not a pro in 3par as you can see

You need a minimum of 2 in each cage you install them. If you get two more, you install 2x in 6 different cages (if you have that many). If you only got 4 cages and you're stuck between a rock and a hard place. I would put 6x in each node cage. Having 4 SSDs in one cage and 2 in the second is worse than having 24 FC drives in one cage and 18 in the second.

[3parnewb]

Yes I have 8 cages in total.

Can you also help me with how I can remove the HDD's + free up licenses the right way? Last time I just pulled a drive and that's not the way haha. Had to do a lot of repair.

[MammaGutt]

Yes I have 8 cages in total.

Can you also help me with how I can remove the HDD's + free up licenses the right way? Last time I just pulled a drive and that's not the way haha. Had to do a lot of repair.

Long story short you need to set the PDs to ldalloc off, then move all chunklets off the drive, remove spares before dismissing the PD.

I’ve seen a excel spreadsheet in this forum a few times but I never got the command that supposedly should move all chunklets for you to work….