[SOLVED] DRBD question

[VyreX]

Hello, i plan to suggest a proxmox solution to my client but im not sure of one thing about DRBD, and before i outline it to him i would like to ask for some pointers.

i.imgur.com(slash)6qu2L9Q.png <spam filter bypass

Here's a really basic outline what i want to do. Two identical servers in two places running same hardware and setup. My first plan was to replicate ZFS periodically (once a day probably) but then i heard about DRBD. Can i use DRBD as a replication service and not as a redundancy service? My plan for redundancy in case of main server failure was to let someone drive to the second site, grab the replicated server and replug everything back on the main site. I cannot use DRBD as a failover because i plan to use the server as a router too so if server fails, connectivity in the main site also fails. Separate router is probably not an option due to cost associated with another server needed for that (unless you know how to do it on the cheap).

I know this is quite janky solution but the business of my client is quite small atm. (around 12 devices 8 users) and cost constraints are quite high.

Main site internet is around 125Mbits symmetric and second location hasn't been decided on yet but expect home location with limited bandwith around 30/10 down/up. No data caps. Daily data throughput wouldn't be big 10gb at most with occasional larger spikes up to 50gb every few weeks.
For the servers i plan to use refurbished poweredge dell servers, i haven't decided on the exact hardware but don't expect something spectacular 2x quad core Xeons, 32+ gb of ECC ram, 3-4 gigabit network ports. ZFS pools will be around 10TB (space needs werent discussed yet) and i plan to keep VM data of Zentyal and pfsense on freenas and keep proxmox and freenas data on mirrored sata dom 32gb (also replicated onto zfs pool).

I already discussed it with few of my colleagues and general setup seems okay but if you spotted some major flaw please tell me.

Also to recap my main concern:

Can DRBD be used as a replication service so when main server fails and someone brings second server and replugs everything will it work plug and play?

Thanks !

 

[LnxBil]

Separate router is probably not an option due to cost associated with another server needed for that (unless you know how to do it on the cheap).

Depends on your needs but a simple Wifi router with GBit and OpenWRT is also very cheap.

Can DRBD be used as a replication service so when main server fails and someone brings second server and replugs everything will it work plug and play?

Assuming you have the same IP address for your servers in both networks and synchronize the configurations, then it should.

The thing is, technically your solution should work, yet the performance bottleneck is huge. If you want the synchronous replication features of DRBD, which is as I understand you the main idea behind using DRBD, you have to know that a write to your storage is only finished if it is written on the other side as well and was reported as written to the first node. This means that you have to have a blazing fast internet connection, whereas I'm talking about latency, not bandwidth.
To solve the bottleneck, you have to use asynchronous replication, yet this is also done via ZFS directly, so you do not gain much in this department.

Either way, you should also have encryption in place in any case :-D

 

[VyreX]

Depends on your needs but a simple Wifi router with GBit and OpenWRT is also very cheap.

Heh, Its how it's currently setup. What i mean't by router on the cheap i meant separate pfsense box to handle all networking stuff.

Either way, you should also have encryption in place in any case :-D

I might look into ZFS encryption but honestly data security is not required in this company. No sensitive data is held nor there are any compliance issues.


Thank you for explaining how DRBD works, i must've had a different understanding how it works. I will go with ZFS replication then.

I will go ahead and mark this as solved. Thanks again !

 

[LnxBil]

honestly data security is not required in this company

Hmm, you don't have federal laws about that? e.g. in Europe, there will be EU regulation 2016/679 which forces all member states to have a General Data Protection Regulation (GDPR).

 

[VyreX]

General Data Protection Regulation (GDPR).

Thanks for telling me about it, I had no idea about this. I will have to look into this much closer than i thought plus ask a lawyer for advice.

 

[LnxBil]

I will have to look into this much closer than i thought plus ask a lawyer for advice.

Yes, this is going to be the next gold rush for lawyers.