@dafyre said in Linux: The Role of DRBD:

@scottalanmiller said in Linux: The Role of DRBD:

I added a header into the main topic list for that. But it is going to be later in the Advanced Topics, section. Oddly, I know of pretty much no standard Linux Administration tomes that cover DRBD. It's so core, very odd that it so often gets missed.

Could it be that most Linux Admin's don't know about it until they go searching for it? ...That's how I found out about it.

You would hope that the people writing the books would know, though!

Of interesting side note, the Linux md RAID system also implements Intel Matrix RAID and DDF (Disk Data Format) software RAID formats commonly used by consumer FakeRAID systems. Because of this, Linux md can sometimes convert FakeRAID into enterprise md RAID if you really know what you are doing 🙂

Remember that this is backup. So if the backup system fails you have options like...

Taking a new backup from the live systems. Offlining the limping array and taking a full backup of it before attempting a restore Doing a backup/restore rather than an array recovery

All of these things make RAID 6's risks minimal. This isn't the only copy of anything, it's a backup. And it is not subject to availability risks (at least not in the way that live data is) so things that cause availability issues are not significant.

@scottalanmiller said in How to Market RAID 6 When Customers Need Safety:

@DustinB3403 said in How to Market RAID 6 When Customers Need Safety:

@BBigford said in How to Market RAID 6 When Customers Need Safety:

I once asked a vendor who were pitching an appliance that supported RAID0+1 and RAID1+0, "what would you recommend between the two, to a potential customer?" They said it didn't matter as they are both the same thing.

We didn't go with that vendor.

RAID10 vs RAID0+1

Or, you know...

http://www.smbitjournal.com/2014/07/comparing-raid-10-and-raid-01/

TL:DR pictures are prettier 😛

Getting lots of eyes on this thread today. Very interesting.

No, it doesn't support this. RAID 1, you are correct, but Parity RAID 5 or 6 it does not. The OS needs to be up and running to be able to manage the parity RAID so you can't use it for the system install, only for extra data volumes.

@tonyshowoff Now that's just painful to think about.

@Kelly said:

@scottalanmiller said:

Did it rebuild successfully?

I don't know. I ended up setting up the necessary VMs on other hosts and started rebuilding this one since it has been having stability issues in the last few weeks.

Ah okay, probably best but it is nice when you can figure out what happened, just to know what it was 😞

0_1470719904433_-its-a-silly-meme.png

@DustinB3403 said:

Here is the definition.

http://mangolassi.it/topic/6816/hot-swap-vs-blind-swap/2

Now which applies to MDADM RAID? If Cold swapping is the only way of swapping drives, then I guess it immediately excludes it from any Enterprise or even business solution.

MD RAID (MDADM is the management utility for MD RAID) is hot swap, of course, and some vendors like ReadyNAS and Synology add their own extensions to add blind swapping. No one would even discuss it if it wasn't hot swap.

@BRRABill said:

I'll check those other ones out.

Oooooh looks like I have some reading/Googling to do!

I usually just power off the server, yank all the drives out, mix em all up and put em back in. I also enjoy testing my backups quite often.

I'll have to try your method next time!

😉

@Dashrender said:

@dafyre said:

@Dashrender said:

Why are we even talking about this POS?

Because you can?

because we can waste our time? I guess.

We're not wasting time. We're waiting for replies to other important topics. 🙂

@anonymous said:

Does anyone make a cheap raid card?

Inexpensive raid card no. Inexpensive HBA card, yes.

Ended up revising my approach to the whole configuration. I bought an SM951 128GB for the caching device and grabbed a pair of seagate 2TB drives and put them in an md raid 10. Random 4k inside one of the VMs averages between 12,000 and 20,000 write depending on queue depth. This seems low given that the SM951 is rated really high, can bcache be tuned to increase the dirty cache for random io?

I did manage to find a setting for sequential which pushed it up to 1GB/s.

The one big difference is that snowflake firms (or any size) tend to lean towards platform-based, agentless backups while DevOps firms almost never take platform-based backups because they have no need to ever restore a full VM, only the data.

@Reid-Cooper said:

@MattSpeller said:

@Reid-Cooper said:

@BRRABill Can't be more than $2!! Right? Memory at that size is so freaking cheap!! Seems like 2GB would be a more logical minimum size.

$2 multiplied by 500,000 units - not going to happen lol

You can easily charge $3 for that kind of upgrade, though!!

Then how do you upgrade them to the WD My Cloud EX5? 😉

@dafyre said in Hot Swap vs. Blind Swap:

@scottalanmiller said in Hot Swap vs. Blind Swap:

@dafyre said in Hot Swap vs. Blind Swap:

@scottalanmiller said in Hot Swap vs. Blind Swap:

Intel has started calling Blind Swap - "Surprise Hot Plug".

Because you're surprised when you blindly swap the right drives?

The system is surprised, to say the least.

Also: Holy Necropost, Batman!

Ha, but with new updates.