@connorsoliver said in An Overview of RAID - CompTIA A+ 220-901 220-902 Video Training by Prof. Messer:

Is using a RAID 1 configuration faster as well? Or is its main purpose so if you lose one of the drives you have a backup?

Primary purpose is definitely data protection. But RAID 1 provides a 200% read performance benefit over using a single drive. Write performance is the same as a single drive.

@PhlipElder said in Raid10, must use or another Raid limits?:

Modern RAID controllers have the horsepower and cache RAM that is flash backed to overcome any real parity performance costs.

Operationally it would be just fine. It's only recovery time that would be of concern.

@scottalanmiller said in Dell MD1220 RAID 5 Rebuild Question:

@Jimmy9008 said in Dell MD1220 RAID 5 Rebuild Question:

@scottalanmiller said in Dell MD1220 RAID 5 Rebuild Question:

@travisdh1 said in Dell MD1220 RAID 5 Rebuild Question:

That makes a little more sense. They've negotiated a deal with Microsoft from the sounds of it.

No, way, way more likely they just figured out how hard it is to get caught.

I totally doubt anything like that is going on here. I have been told our annual budget for licensing which we pay is in the region of £600,000. Either way, not my problem 🙂

Wow. But, sounds like only that high because they don't know what they are using, lol. The only way to get licensing truly down is to know what you use. Someone is both ignoring what is used, but also encouraging unlimited use. Both things set MS up to just keep making it more and more expensive. It's a trick, sounds easy, but makes one lazy licensing person encourage not keeping licensing lean - basically giving Microsoft the power to charge anything that they want down the road.

Yeah, not your problem, but definitely a symptom of management issues and a lack of clear thinking. If they are truly paying their bills, my guess is a licensing "specialist" who has created their own job and knows if MS isn't used heavily, their job would go away, so is doing stuff to encourage you to lock in MS so that that specialist can't be eliminated. Basically creating their own job.

Yeah, I don't disagree with anything you said. It's just not my issue. I still get to buy shiny new toys 🙂

@Emad-R said in Linux NFS SSD caching:

AID 10 on Linux File Server machine, how can I speed up this NFS storage by an intelligent
cache, for example I wish to add another 250 GB SSD to act as cache, how will tha

Yeah the RAID 10 is on HDD, due to cost effectiveness. Will check LVM since its baked in.

Oh dear.....{sigh..}

@scottalanmiller said in Battery Backup with SSD raid:

@pete-s said in Battery Backup with SSD raid:

@scottalanmiller said in Battery Backup with SSD raid:

@pete-s said in Battery Backup with SSD raid:

@scottalanmiller said in Battery Backup with SSD raid:

SSD NV protection is to allow the SSD's cache to flush safely should power be lost. RAID NV / battery protection is to allow the RAID's cache to flush safely should power be lost. Each is important on its own, neither covers for the other one.

That's technically slightly incorrect.

The non-volatile cache memory on the raid controller is to be preserve the data that has not yet been written to the drives, until power is restored again.

On the SSD the capacitors hold enough charge so that the drive can write the remaining data in the cache memory to the actual flash memory after the power is gone. The cache is DRAM so it will loose it's contents after a few seconds.

The only time details like this matter is if you remove the battery from a raid card, your data might be lost.

I'm missing how that is different than what I said. What you said is correct, but I feel like you just reworded what I said, with the added detail that the RAID card flush is not until power is restored, which one hopes is obvious.

Sorry Scott, you're right. I was just thrown off by you said "SSD NV protection" and because you worded both thing the same. Obviously both things are to protect from data loss at power failures.

OIC, you are saying that the SSD is volatile, but has a battery in most cases? makes sense.

Almost, let me explain. Below is a picture of an Samsung enterprise SSD, SM863.

The SSD controller (yellow) is the brain. The flash memory (green cross) is non-volatile so it will not suffer data loss without power. There are also more flash memory on the backside.

The cache memory however is the blue ring and it will lose it's memory as soon as the power is removed. It's the same type as the memory in your computer, DRAM. That would cause immediate data loss and that is not good and that is why enterprise drives have a lot of capacitors (red circles).

The capacitors (red) act like small rechargeable batteries. When the drive loses it's external power these small capacitors will work as a reserve power for the entire drive. The controller (yellow) knows that it has lost external power so it will quickly write the data from the cache memory (blue) to the flash memory (green) before the reserve power from the capacitors (red) are empty. That way data loss is prevented. This will only take a couple of seconds at most.

0_1538765396271_samsung_ssd.png

@wrcombs said in IDE as a RAID?:

@scottalanmiller said in IDE as a RAID?:

@wrcombs see, that was easy, lol.

LOl UP to 40% now.. after .. hours... This isn't gonna be done today..

Cheap RAID can be VERY slow.

@obsolesce said in Does Dell not offer low cost HW RAID anymore?:

@dbeato said in Does Dell not offer low cost HW RAID anymore?:

@obsolesce said in Does Dell not offer low cost HW RAID anymore?:

@dbeato said in Does Dell not offer low cost HW RAID anymore?:

@obsolesce said in Does Dell not offer low cost HW RAID anymore?:

@dbeato said in Does Dell not offer low cost HW RAID anymore?:

Plus MD1000 are for older SANs...

eh? It's just extending the internal storage... externally, hence "DAS". It has tons of use cases.

It does, but they MD1000s were mainly setup for SAN devices in mind. Yeah they can also be attached to servers as well which is not bad either. Just not my preference, nothing wrong with that.

Not sure what you mean, a DAS is a DAS... MD1000, MD3000, MD1200, MD1400... whatever. They are simply (as what Dell calls them, @scottalanmiller , not me) "Server JBOD Expansions". They aren't specific to SAN use and are not SANs.

Okay, I am not trying to go in a tangent and go in argument with you. Why does it need to be this way?
Reason for me saying that mainly Dell uses it for SANs see below:
https://www.dell.com/en-us/work/shop/povw/powervault-md1000

You still can use them for servers for user.

No arguing or disagreeing... I'm just not understanding where you're getting "SAN" from?

0_1529507862093_2018-06-20_11-17-09.png

Yeah after my limited experience with this, not sure I would ever trust using a non-DELL drive.

At least on a production system.

It's using the Intel controller. . .

powershell.exe get-disk

@krisleslie said in Adding additional Drive to XenServer host, get error:

@black3dynamite i use 1 hdd 😞

I meant virtual disks. VM1 with virtual disk 1 = OS and virtual disk 2 = data

@momurda said in Intel's NVMe VRoC System Now Out:

If an SSD is rated at 1DWPD for 5 years and in actual use one only uses .2DWPD, does that mean that such an ssd would nominally last 25 years barring some other catastrophic hw failure not related to the destructive nature of flash program and erase cycles?

All reliability is about chances of failure. So it’s likely to last that long.

@scottalanmiller

Yh by accident today I was able to understand it better

2_1518718280839_2018-02-15 20_02_46-Fedora OBR10 - VMware Workstation.png 1_1518718280837_2018-02-15 20_02_41-Fedora OBR10 - VMware Workstation.png 0_1518718280836_2018-02-15 20_08_13-Fedora OBR10 - VMware Workstation.png

Fedora suffers the same fate as centos, and wants to error out but instead when it does not see the boot partitions it will error out quickly then check the next drive, and if it founds it it will update the EFI parition and add another line so it has fail safe method, centos wont do this. so the 1st entry belonged to boot part that was deleted and the 2nd as well, so fedora will keep finding them if you have them and it will auto update the EFI parition while it boots up and adds another line, so then you can boot normally. all this done in the background, you will just see an error fail for boot for 1-2 seconds they you will boot normally cause Fedora already written another entry.

I am starting to like Fedora for servers (minimal install) and if I want centos I can use it as guest vm.

@scottalanmiller said in RAID - the king of the storage landscape or legacy?:

@pchiodo said in RAID - the king of the storage landscape or legacy?:

Well, I think you guys really RAIN'd on this guys parade. Good work.

You were hoping for a RAIDing party?

~Grabs Knife of Slicing. (Knife made from computer case, +2 bleeding damage)
~Grabs Winchester Shield (+1 defense, -255 data retention).
~Grabs Umbrella (+50 resistance to water, -50 resistance to lightning).
~Grabs Book of SPELLS. (Stupidly Powerful Extra Long Ludicrous Sayings, +25 Magic Damage)

There, I'm ready.

@popester said in Hybrid RAID SAMIT Video:

@scottalanmiller sounds like a "Hot Mess"

Pretty much 🙂

Instantaneous Storage Evacuation Event

This is totally a coincidence that this was the next one up in the queue to post here. But talk about perfect timing! This came up at least three times today alone.