4TB limitation on volume replication

[masim]

Hi...

Kevin - thanks for the nice info... but can you explain this:
I am replicating 2.8TB and getting an average steady speed of 62MB/s.

if what you are saying is right, then what I am getting is impossible...

Any one else can confirm this???

[To-M]

Here let me help Keven out as he wanted to place his trophy on our response (yes should have been better but without the blood).

Here is a better description and using Protocol C is better in the end. If you don’t like it build it yourself .

For each device, drbd will (try to) allocate X MB of bitmap, plus some constant amount (<1MB). X = storage_size_in_GB/32, so 1 TB storage -> 32 MB bitmap.

By default Linux allocates 128MB to Vmalloc. For systems using more than 4TB, this may cause an issue - but give us time as we resolve this!!! It will happen, we are not going to just update without hard testing with our main customers unlike what some want it now.

[To-M]

And yes asynchronous is in the works - very soon

[rykerlee]

We are replicating with 2 x 4TB volumes and haven’t had any issues for over 68 days, though we are using DSS ver. 5.0_42 in block io mode.

Not sure if this helps others but on a side note we would have more interest in what Heimic and SeanLeyne stated then the 16TB replication option (DRBD+). Vkeven must be needing something other then what DSS provides currently or wanting blood like Todd said

Todd - any chance that we will see asynchronous soon (not asynchronious )?

[To-M]

Long time no hear from U!

We want to say mid part of Q2 - though if there are issues or pending projects (especially from you guys for those huge orders ) then all this delays it.

[masim]

Man you are good...

Now i did some research and found that protocol A asynchronous is a completion of request happens as soon as it is completed locally and handed over to the local network stack. In case of a Primary node crash and fail-over to the other node, all WRITEs that have not yet reached the other node are lost.

hopefully this is helpful

Again thanks Todd for these quick responses...

[To-M]

also some must go to vkeven for starting this thread.

[vkeven]

How much people has understand the way Open-E replication work before I post this thread?
In just one post I get interest of real power users of Open-E ( the one that want more than 4TB ) , but Open-E is not happy when I'm posting something that could be true , even if I try to contact support I reach a dead end , forum are suppose te be use for discussion,idea,limitation but as long as Open-E don't get hurt. Maybe we should start a user forums of Open-E?