https://i.imgur.com/pKIH8je.png

@scottalanmiller said in Matching Drives for RAID:

*Under the Hood: RAID arrays effectively use all of their devices in lock step. Whether you have two drives or eighty in your array, all of them go and look for one block of data together and they all way for the slowest drive in the array to return its block before continuing on. When all drives are identical, they all read and write at the same time and we basically get full performance from every device.

A minor change to be more accurate

*Under the Hood: RAID arrays effectively use all of their devices in lock step. Whether you have two drives or eighty in your array, all of them go and look for one block of data together and they all wait for the slowest drive in the array to return its block before continuing on. When all drives are identical makes and models, the differences are much smaller between them and we get closer to full performance from every device.

Of course, in more modern systems, the use of advanced LVMs instead of older partitions makes this a little more flexible so that more control over the process can exist. But all of the core problems still exist.

Some vendors try to market this mechanism as "RAID virtualization", which isn't a completely crazy name due to the layers of abstraction, but it makes it sound valuable when, in reality, it is not. RAID virtualization when used for the purpose of enabling hot or live RAID array growth is generally a good idea. Used as a kludge to enable bad ideas, it remains bad.

Can we get some tags on this post?

URE is one I would love to see added.
Thanks

@black3dynamite said in RAID for Four Disks:

Is most of the confusion about RAID happens a lot more when using it has VM storage?

That appears to be the case. Virtualization and RAID seem to just universally confuse, I suppose.

Someone looking at this thread had a hard time figuring out how to open the registry editor after booting to CLI mode from the 2008 R2 media. from the command line, type regedit and hit enter, it will load.

@Dashrender said in Announcing the Death of RAID:

@scottalanmiller said in Announcing the Death of RAID:

What you are thinking of is my recommendation for supported drives that are part of the system itself if you are going for a warranty supported system like from Dell or HPE. Bringing your own drives would push you to vendors like SuperMicro where you can mix and match for the best performance, cost and features.

I want to ask why we can't/shouldn't use consumer class drives in a Dell or HPE server, but I think the answer might be - because if you're paying for that level of support, why are you not going all in?

Is that right?

i.e. if you want to run your own performance/cost factors, you're better off starting with a SuperMicro, is that what you're saying?

Yes. That's what I mean.

One of the confusing pieces here is that Linux actually does things more clearly but the Windows world is so confusing that if you carry that confusion into the Linux world, it makes things harder. Windows rarely uses or discloses the names of their product components. So Windows Software RAID is used to describe part of the Windows OS. But what if you have software RAID on Windows that is not Windows Software RAID? Windows Admins typically have no good terminology to discuss this, even though it is common. They just.... don't know what's going on and don't document it. But in Linux, we have the terms on hand all of the time (MD, ZFS, whatever.) So the Linux side isn't as bad as it seems, but if you are used to a weird blend of generic names being used as if they are specifics from the Windows world and assume that the Linux world is just as crazy, then it seems crazy.

@tjatwood109 said in ZFS is Perfectly Safe on Hardware RAID:

@scottalanmiller

Thanks - I will proceed without using ZFS - I prefer hardware RAID.

Tim

ZFS is perfectly fine with hardware RAID, if you like ZFS' features otherwise (like zsend is nice) then there's no reason to avoid it. If you don't plan to use any unique features, then XFS is my "go to" choice by default. Very fast, very stable.

@coliver said in Why the SMB Still Needs Hardware RAID:

@scottalanmiller said in Why the SMB Still Needs Hardware RAID:

@coliver said in Why the SMB Still Needs Hardware RAID:

@scottalanmiller said in Why the SMB Still Needs Hardware RAID:

@coliver said in Why the SMB Still Needs Hardware RAID:

@scottalanmiller said in Why the SMB Still Needs Hardware RAID:

@coliver said in Why the SMB Still Needs Hardware RAID:

@travisdh1 said in Why the SMB Still Needs Hardware RAID:

@dafyre said in Why the SMB Still Needs Hardware RAID:

@scottalanmiller said in Why the SMB Still Needs Hardware RAID:

The most common RAIN approach that I see is taking all disks in the pool, noting their nodal presence and using mirroring to distribute the data so that data mirrors never go to the same disk and/or the same node. So a little like a networked RAID 1E but with more flexibility and the option to add nodal separation and performance testing so that data moves to where it is used.

Are you aware of any open source RAIN systems?

Gluster and Swift

I think Ceph and Lustre may be two others.

Lustre is RAIN, but is closed. Gluster was the open replacement for Lustre.

Just a quick search showed that Lustre was GPL 2.0, not sure if that is new or not.

Oh wow, must be new. It was crazy expensive in 2006 when we were really investigating it. That's awesome.

Ah looks like it went open source in 2010.

Oh cool, so I remember things well then. I'm just out of date. Gluster probably forced their hand, why would anyone consider Lustre when it was closed source? The answer was probably... they wouldn't and didn't.

Yep, I'd assume that was the case. Especially when it is a such a specific, and at the time, niche market.

And when Gluster went directly after them, even in name.

@FATeknollogee said in XenServer 7.0: monitor hard drive failure:

Since the Dell fanboi's hijacked this thread (jk 😃 ) I'm going to start another thread.
Actually have some good info for those of us non-Dell users.
I use SuperMIcro.

Is there anything about Dell on here? Dell was mentioned, but nothing Dell specific was said. All of the info applies to SuperMicro as well. IPMI is used instead of iDRAC. And the PERC software and the LSI MegaRAID software is the same. Only difference is branding.

@dafyre said in Can You Install FreeNAS to a Single RAID 6 RAIDZ2 Array:

Who are you and what have you done with @scottalanmiller ... Actually using FreeNAS for something?

I was just about to say the same thing. Or maybe his account was hacked.

This is the mobo that this will be connected to:

http://www.supermicro.com/products/motherboard/Xeon1333/5000P/X7DB8.cfm

@Dashrender said in RAID 10, 20 Disks, How Many Hot Spares:

So is it done? Does Matt understand and agree to the point that Scott was making?

Yes I believe so.

TL;DR attempt #1 #2 #3 #4 (counting edits)

RAID10 does not need hot spares

If you have spare slots you'd be better served by a larger array with more IOPS

The corner case (the one raised by the op's question?) is would hot spares reduce the risk of array failure. The answer is 100% absolutely yes it will reduce the risk of failure.

The disagreement (I think..?) was if that's necessary. We agreed that it isn't necessary to have any hot spares for RAID10 unless there's mitigating factors (examples: remote COLO with horrific access issues, extremely risk averse use case).

@Texkonc said in PERC H730P Mini - Multiple LV's:

Dustin

Oh ok

@Tim_G thanks

@Shuey said in Invalid Drive Movement from HP SmartArray P411 RAID Controller with StorageWorks MSA60:

Thanks again to everyone who replied and gave feedback on this. It's great to know that there's a solid community of knowledgeable people who are willing to share their expertise - I really appreciate it!!

Sadly we didn't find your solution. But happily you found it on your own!

@FATeknollogee said in XenServer: MD RAID or not?:

Maybe use @francesco provino blog post as a starting point
http://www.francescoprovino.com/2016/09/06/xenserver-7-software-raid-with-mail-alert/

I think that needs a little fleshed out for the newbies.

But yes, that might be a good starting point.

@dafyre said in Rebuild Time on a 96 Drive RAID 7 Array (RAIDZ3):

@scottalanmiller said in Rebuild Time on a 96 Drive RAID 7 Array (RAIDZ3):

@travisdh1 said in Rebuild Time on a 96 Drive RAID 7 Array (RAIDZ3):

Seems like the perfect case to use RAIN, even if it's within a single system enclosure. @StarWind_Software LSFS, I'm looking at you. @KOOLER I am right in thinking this is the sort of thing LSFS could handle, right?

RAIN in a single enclosure rarely does anything that RAID 10 does not. It's effectively all the same at that point (more or less.) If RAID 10 doesn't work, RAIN isn't going to work either (normally.) The issue here is "single enclosure."

Wouldn't a properly configured single RAIN node make it easier to grow when it's time to add more storage?

I've seen this with Exablox and it was a nice feature!

Yes, if you are preparing for scale out. But if you are just doing it within the context of a single node, it doesn't change anything.

Duh here is a guide I actually wrote...

https://mangolassi.it/topic/7785/how-to-configure-gmail-smtp-on-xenserver-6-5-to-monitor-and-alert-about-your-mdadm-array