HA Cluster with SAS and SATA

Chapelhillpc · Thu Aug 14, 2014 7:14 pm

I am wondering if I can setup an HA cluster with one node using SATA drives and the other using SAS?
If it won't work for performance reasons I could have the clients only access the SAS node correct?

robnicholson · Thu Aug 14, 2014 7:30 pm

Yes it will work but I guess your overall performance will limited by the slowest drives. By SAS, do you mean 15k drives or the higher capacity but slower rotation speed nearline SAS? I guess you mean NL SAS as you need a lot of 600GB SAS drives to match the higher capacity of SATA.

Cheers, Rob.

Thu Aug 14, 2014 8:18 pm

You can combine both on the different nodes no problem. We do even have a setup when fast primary storage cluster does offload to a slower one (snapshots). See:

http://www.starwindsoftware.com/whitepa ... iering.pdf

If you run sync mirror between nodes make sure slowest one will have enough of IOPS to handle workload if SAS node will die and SAS-hosted VMs will go on SATA.

Chapelhillpc wrote:I am wondering if I can setup an HA cluster with one node using SATA drives and the other using SAS?
If it won't work for performance reasons I could have the clients only access the SAS node correct?

lohelle · Thu Aug 14, 2014 8:38 pm

We now use SSDs on both node, but we have good experience earlier with one fast node (SSD/SAS) and one slower node.
We manually set the fast path as default for clients, but now we could have used ALUA to fix this automatically.

Reads would always be from the fast node, and even if the slow node had to write the same data as the fast one, large cache would compensate a bit for writes. We could then live with slow(er) performance for some time when the fast node was down (unplanned or planned).

Fri Aug 15, 2014 8:51 pm

With V8 you can step further and can keep clustered HA setup (LSFS or FLAT does not matter) with all-flash and offload snapshots (YES, with this config even FLAT storage does snapshots with a dedicated node) to spindle-based node. See:

http://www.starwindsoftware.com/whitepa ... iering.pdf

Unlike other guys we offload cold data not between slow and fast tiers on the same host but offload cold dat from fast node to a slower ones. Network.

lohelle wrote:We now use SSDs on both node, but we have good experience earlier with one fast node (SSD/SAS) and one slower node.
We manually set the fast path as default for clients, but now we could have used ALUA to fix this automatically.

Reads would always be from the fast node, and even if the slow node had to write the same data as the fast one, large cache would compensate a bit for writes. We could then live with slow(er) performance for some time when the fast node was down (unplanned or planned).