Help with Raid and adding hard drives

[AbnormalSpring]

I am currently building a NAS that has 15 hard drives. Starting with 15 1TB drives to get it off the ground. I am wanting to add 2 more HD for the operating system.

I am wondering if 3 pools of 5 or 1 pool of 15. I also want to be able to swap the 1TB drives up to 8TB WD Blue drives 1 at a time as money permits.

Could I also just add another SAS HBA for 17 drives for the boot drives?

Specs
Motherboard Supermicro X9SCL+-f
CPU Xeon E3 1270 V2
Ram 32 GB DDR3 ECC

Open to any and all suggestions on the raid configurations and anything else. Thank you.

 

[somethingweird]

1 pool of 15 is too wide.

 

[AbnormalSpring]

1 pool of 15 is too wide.

So I would be better off doing the 3 pools of 5. The blue 1tb will be CMR and the WD blue 8TB I believe are CMR but will have to verify before I purchase them.

 

[Etorix]

There's a vocabulary issue here with "pool" and "vdev"… A pool can have several vdevs.
15 is indeed too wide for a raidz# vdev.
5 is not a very good number: Not large enough for space efficiency with raidz2, and raidz1 is advised against as drives go larger.
2 * (7-wide raidz2) could be an idea; possibly with a spare if there are 15 bays. But you need to replace all drives in vdev to expand space, so flexibility here demands narrower vdevs—typically mirrors, for maximal flexibility.

How do you attach 15 drives to a motherboard with 6 SATA ports by the way? 6 plus 8 from a HBA would be 14.

You can have any number of HBAs in a system, but the preferred way is to use expanders on SAS backplanes rather than adding HBAs.

As for the OS, a small SSD, rather than HDD, is advised. Mirroring the boot drive is unnecessary for home use.

 

[jgreco]

Starting with 15 1TB drives to get it off the ground.

A vdev with 15 drives is extremely wide and you may run into issues with resilvers and scrubs performing poorly. 12 is the maximum recommended width before considering multiple vdevs. You could probably do 15 and get away with it not being a total catastrophe, but it's not a good idea.

How do you attach 15 drives to a motherboard with 6 SATA ports by the way? 6 plus 8 from a HBA would be 14.

You can use an SAS expander attached to the HBA, see

Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

With the introduction of SAS 12Gbps, seems like "it's time" to do a braindump on SAS. Work in progress, as usual. History By the late '90's, SCSI and PATA were the dominant technologies to attach disks. Both were parallel bus multiple drop...

www.truenas.com

Through the use of SAS expanders it is possible to add dozens or hundreds of drives to a single HBA. Or use two HBA's. Or use -16i HBA's instead of the common -8i HBA's (8 more SAS lanes on a -16i, 16 more on a -24i).

Could I also just add another SAS HBA for 17 drives for the boot drives?

You can do a variety of things, not all of which are advisable. If you don't mind it being somewhat slow. you can use a USB-to-SATA adapter with a small SATA HDD plugged into one of the USB 2 ports available on that mainboard. This is a pragmatic balance of making the best use of what's available on an older, smaller system. Put one boot drive on USB 2 and one on SATA.