One big RAID 10

[basem]

Hi Guys,

So, I've sized a new SAN that will serves a vSphere Cluster.
MSA 2040, 12 x 3TB SAS 7.2 LFF, MSA 2040, 12 x 3TB SAS 7.2 LFF, since I need 18 TB as a total in addition to good performance with a resilient data-store...
I will create a ob1o, so I'll get 18 TB...
I have eight VMs, each one will be 1.5 TB vmdk...

your opinion please...

 

[dave_the_nerd]

What will your writes-per-day volume be?

A tiered storage system with 18 drives in RAID6 and a couple SSDs as a cache would probably give you better all around performance most of the time, and might manage to be cheaper in terms of $/GB.

If you're rolling your own SAN and want to keep it simple, what you're describing will be the best-performing option you have.

Either way, don't forget to backup, backup, Back Up, BACK! UP!.

 

[frowertr]

So is it 12 disks or 24 disks? I gather it's 12 disks from doing the math (12 x 3TB = 32TB). A OBR10 made up of twelve 3TB drives would thus give you the 18TB of usable space you are talking about.

Do you have your IOPS requirements for each VM? This is the really only surefire way to tell if what you are building will "make sense".

I'm assuming these are 7.2K drives seeing they are 3TB is size. So a 12 disk RAID 10 array made up of 7.2k drives would give you approx 650 - 700 IOPS if it were reading 50% of the time.

 

[basem]

You are totally right frowertr, 12 HDDs, 650 IOPS, someone else advised me not to use 7.2 Disks since it is considered near line, in fact I have multiple VMs that will be at least 1.5 TB so I need size, in addition to that performance are required in some VMs like main MS sql Servers...

 

[frowertr]

There is nothing wrong with Nearline. The only difference between NL-SAS and SAS is disk speed. They are virtually the same exact drive other than the rotational difference. I'd argue NL-SAS is actually more reliable than regular SAS as it is spinning slower and has less wear and tear.

We still don't know what kind of IOPS each VM requires. Do you have this info?

 

[basem]

thank you very much frowertr for you quick help, alas, I have no such this info "IOPS" per VM... I work remotely for the customer and he has no any experience to deliver precise info.. I depend on assumptions

 

[frowertr]

Hmmm. Well Id say the cart was put before the horse on this if you don't know the kind of use the storage will get. What if it's heavy database it needs a couple thousand IOPS??

Is a SAN even needed? Could you not have just expanded the local storage on the current server(s)? I'm wondering what the setup is your upgrading them from??

 

[basem]

OK, I don't walk in the dark,
the current infra consists of some sort of mixed physical servers (old rack+old tower) attached to HP MSA SAN g2...
Will be replaced by HPE DL360 G9 servers + MSA 2040 G4...
the main difference is converting from bare metal to Virtualization...