SAS Multipathing or not ?

[VioletDragon]

In my experience controllers and HBAs rarely fail and even if they do you are unlikely to permanently lose your whole pool as a result. I would suggest you are more likely to come to harm by trying to make multipath work on an appliance that the creators themselves have given up on.

Interesting. How many drives can I lose up to when I have 4 mirrored vdevs ?

I plan adding two more too.

 

[Johnny Fartpants]

If you mean a 4 x 2 way mirror then you can lose one drive in each vdev before losing your entire pool.

 

[VioletDragon]

If you mean a 4 x 2 way mirror then you can lose one drive in each vdev before losing your entire pool.

My Pool as Follows, I plan on moving mirror 2 and 3 to the JBOD

Code:

 mirror-0                                          ONLINE       0     0     0
        gptid/bf59a5cc-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/bf9ee635-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c0c51c7a-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
      mirror-1                                          ONLINE       0     0     0
        gptid/c0f533ba-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c11a2a79-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c1b58159-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
      mirror-2                                          ONLINE       0     0     0
        gptid/c0b553b5-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c16c10b5-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c19dea70-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
      mirror-3                                          ONLINE       0     0     0
        gptid/c0219ef2-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c01956b2-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0
        gptid/c05444bb-4e00-11ed-89fb-d4ae527d0f3e.eli  ONLINE       0     0     0

 

[Johnny Fartpants]

Ah ok so you have a 4 x 3 way mirror. So you can lose two drives in each vdev before losing any data. However if you unfortunately lose 3 drives in one vdev then you have lost your entire pool.

This is an unusual layout, may I ask why you have arrived at this?

 

[VioletDragon]

Ah ok so you have a 4 x 3 way mirror. So you can lose two drives in each vdev before losing any data. However if you unfortunately lose 3 drives in one vdev then you have lost your entire pool.

This is an unusual layout, may I ask why you have arrived at this?

Well how else can you configure it? I thought having more Mirrors makes it better that's from what i've read also improves Read Performance, I plan on adding more drives to this too. It's a array that is used for Block Storage to a 3 way Hypervisor Cluster.

 

[Johnny Fartpants]

More vdevs makes better performance. If random IO is key then yes two way mirrors would make sense however if sequential R/W is needed then I would go for RAID-Z2 perhaps 6 disks in each.

You are losing a lot of space having three drives in each mirror.

 

[VioletDragon]

More vdevs makes better performance. If random IO is key then yes two way mirrors would make sense however if sequential R/W is needed then I would go for RAID-Z2 perhaps 6 disks in each.

You are losing a lot of space having three drives in each mirror.

From what i've read it is better to go with Mirrors instead of RAIDZ and as there are Database Servers I choose to go with Mirrors. So should I have just two disks per mirror then more Mirrors ?

 

[Johnny Fartpants]

If performance is the main aim then yes, I would.

 

[VioletDragon]

If performance is the main aim then yes, I would.

2 Disks per Mirror and more mirrors will give me more storage too ? I plan on adding a SLOG Drives too.

 

[Johnny Fartpants]

Yes. SLOG would make sense for block.

 

[VioletDragon]

Yes. SLOG would make sense for block.

That is one of the reasons why I am installing a Disk Shelf so I can add SLOG drives.

I am guessing that with more vdevs it will give me more Storage too. Just one question, What would happen if I loose all drives in Mirror 4 and 5?

 

[Johnny Fartpants]

What would happen if I loose all drives in Mirror 4 and 5?

You would lose your entire pool.

 

[VioletDragon]

You would lose your entire pool.

Yeah that is my concern with just using one module in the disk shelf :/ unless I put one disk from per mirror in the disk shelf ?

 

[Johnny Fartpants]

unless I put one disk from per mirror in the disk shelf ?

Yeah you could do that.

 

[Johnny Fartpants]

I look at it the other way round. I like to keep my pools in the JBODs as if the server fails I can just connect to another server and import the pool.