4TB limitation on volume replication

[heimic]

Hi,

a drbd+ option would be fine, not for replication >=4 TB filesystems, but for the 3rd mirror desaster recovery (DR) option, so we would be able to have an additional DSS server on our DR site.

regards
heimic

[SeanLeyne]

Hi,
a drbd+ option would be fine, not for replication >=4 TB filesystems, but for the 3rd mirror desaster recovery (DR) option, so we would be able to have an additional DSS server on our DR site.

Same here, support for a 3rd mirror would be _very good_. Ideally, we would want a failover-failover-failover scenario which had 2 DSS in our server room and a 3rd at a DR site.

[vkeven]

I think its the time for a more "enterprise" version of Open-E , DSS Standard for very small business and a DSS Premium ( with DRBD+ and more control of things inside Open-E ) for bigger one with some sort of priority support contract.

[To-M]

The engineers will have this capability to replicate beyond 4TB (no set time frame for which release - but they are working on it) they will need additional time as we recognize the need for this.

[vkeven]

at the same time if they could use the fonctionnality of DRBD+ 3rd site asynchronious replication this would be a must!

Do you know wich protocol of DRBD ( A,B,C) Open-E is using for replication processus?

Thanks
Keven

[To-M]

We use protocol C - engineers found it to be faster than others.

Our kernel uses 10-20 MB of the Vmalloc memory. The replication Vmalloc usage is about Volume Size/32768.

[vkeven]

Wrong DRBD need 32MB of vmalloc by 1TB of storage, the formula is storage_in_GB/32 and not by 32768 so 4096GB/32 = 128 so I don't know if some people have a rock solid replication volume over 1TB but from the maker of DRBD 10 to 20MB is clearly not correct.

Read this post about memory allocation and 32MB by 1TB , the writer is the PROGRAMMER of DRBD Dipl-Ing Philipp Reisner so I don't know if your enginnier are reading this forum or even DRBD doc and mailing list but I think they should do , 32K by 1GB of storage so 1TB=1000GBx32Kb=32000Kb=32MBx4(for 4096GB or 4TB)=128MB,now I know why people complaining about replication stop working.

Just for Information Protocol C is probably the slowest one but the most secure for your data , so this is good , a control of protocol could be an interesting option , like protocol A for asynchronious remote site.

http://www.drbd.org/users-guide/s-re...protocols.html