hardware ceph question

[ilia987]

i planning to add some more nodes to the grid ( we need mainly more computational power cpu\ram )
but i thought to add an HDD ceph storage for low accsess\archive storage (we have existing 5 node ssd based servers for to support heavy read tasks )
i am thinking to do the following 3x 6027TR-D71RF+ ( total 6 more ceph servers each with 6 HDDs)

 

[ph0x]

... and your question is?

 

[ilia987]

Right I forgot .

Is it a good idea to make multiple ceph agents with small amount of osds. In this case each will have up to 6.

Or better to get server with better capacity. (More hdds sleds )

 

[ph0x]

I would say that a Xeon E5 can easily handle more than six OSDs, on the other hand there's more failure tolerance with more hosts, so this remains up to you.
You said you wanted to add mainly compute power. Then I would recommend fewer OSDs per node to not waste the power on storage tasks.

 

[ilia987]

do i need another lsi card? or the onboard is good enough ?
i plan one of the following models 6027TR-DTRF+ 6027TR-D71RF+ 6027TR-D70RF+

 

[ph0x]

SAS2 is 6 Gbps, just like SATA3. In order to facilitate 12 Gbps you would need another HBA, yes.

 

[ilia987]

The plane is to use HDD (not ssd, so 6gbs should be good enoth) for ceph storage. so for 6gbs can i use the onboard controller to work with ceph?

 

[ph0x]

I didn't test it but I don't know why this shouldn't work.