8 disk and more with vsan

[b4ndit]

Hi,

I have question about vsan design.

If we need more than 8 disks per host for vsan does it need to have more than 1 disk controller ?

I think I have read somewhere that vsan is not recommended using sas expander.

Could someone able to share their experience about this ?

Thanks

[Matt Brown]

Can't speak for other manufacturers but all of our HPE VSAN nodes (DL380 G9) use SAS expanders.

Nodes at the primary site are fully populated for disk (4x SSD and 20x HDD) and DR nodes are 50% populated. No issues at all.

Matt

EDIT: Nodes mentioned above are certified as VSAN Ready

[SureshKumarMuth]

Hi ,

VMware official guide says the following

Multiple controllers and SAS Expanders Virtual  SAN  supports  multiple  controllers  per  ESXi  host.  The  maximum  number of disks per host is 35 (7 disks per disk group, 5 disk groups per host).  Some  controllers  support  16  ports  and  therefore  up  to  16  disks  can be placed behind  one  controller.  The  use of two such controllers  in tne  hos t  will get  close  to  the  maximums.  How ever,  some  controllers  only support 8 ports, s o a total of 4 or 5 con trollers would be needed to reach the maximum.

SAS expanders  are  sometimes  considered  to  extend  the  number  of  storage  devices  that  can  be  configured  with  a  single  s torage  I/O  controller.  VMware  has  not  extensively  tested  SAS  expanders  with   Virtual  SAN,  and  thus  does  n ot  encourage  th eir  use.   In  addition  to

potential  compatibility  issues,  the  use  of  SAS  expanders  may  impact  performance  and  increase  the  impact  of  a  failed  disk  group.

  SAS Expanders  have  been  tes ted  in  limited  cases  with  Ready    Nodes  on  a  case  by  case.   Thes e  ready  nodes  may  have  a  ‘‘up  to’’   maximum on the number  of  drives  that  have  been  certified  with  the  expander.  Refer  to  the VSAN VCG to  see  what  SAS  Expanders  have  been  certified  and  will  be supported

Doc: http://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/products/vsan/virtual-san-6.2-design-and-sizing-guide.p…

page :47

However, I have seen environments where SAS expanders are used and it works fine provided the components/firmware/drivers are in supported level as per VSAN configuration guide.

[Evan5]

If you're asking if you can have more than 8 disks in a host and if your host can accommodate more than 8 disks natively then you simply just create more than one disk group on the host.

If you do this the only limitation is that you will need one SSD drive per disk group if its a hybrid vSAN, so you might need to buy another SSD drive if that's the case.

One controller on the host should be able to accommodate all disks in the server, the fact that you have more than one disk group makes no difference to the controller.

Not sure if that is what you were asking but hope it helps anyway.

[zdickinson]

Good afternoon, if your controller can have multiple connections and your host can have more than 8 disks attached, what you do is have multiple disk groups.  For instance we have 16 disks in our hosts with 1 controller.  Thank you, Zach.

[b4ndit]

We are not going to use vsan ready nodes because non technical issues.

Okay, I think we better go without sas expander, which means we need more disk controller.

Thank you all.