This is how drive testing is such a deep topic. You need to try and match the load, and consider all the things. CrystalDisk does not do that.

You can set up some really good tests with iometer. (I think that's waht it's called, i can't remember now it's been a long time and can't look it up atm)

@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 just upvote and quote me. 🙂

Slowpoke.

@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.

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

@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).

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.

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

@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? 😉

@alvama said:

Scott, thank you for your topic. I am planning new installation and comparing between RAID 10 and RAID 5 on ssd drives. What do you think about stripe size and TBW for two types of raid? Do you know what size of blocks will be written on disks if service (sql for example) writes 8Kb on volume. For raid10 I think it will be two 8K blocks on mirror disks. But for RAID 5 it will be two blocks with size=stripe size and may be 32 or 64K. And in raid5 configuration TBW limit will be reached faster.

I'm not Scott but in your context RAID5 seems to be preferred. Because 1) Flash and not spinning disk used so typical parity RAID issues associated with high-capacity spinners are gone (see URL below) 2) Database logs are sequential writes of a big sizes so should "touch" maximum amount of spinners possible and because of sequential nature read-modify-write is not going to happen and 3) RAID5 gives you write performance of (N-1) and RAID10 does (N/2) (where N = amount of spinners).

https://slog.starwindsoftware.com/raid-5-was-great-until-high-capacity-hdds-came-into-play-but-ssds-restored-its-former-glory/

Good luck 🙂

@scottalanmiller Planning to start it this week.

I'm still finding parts to use. Trying to be as cost conscious as possible as this is only my home lab. (and the significant other gets testy when I want to "buy toys")

He's from NZ. We've spoken offline before.

@scottalanmiller said:

@dafyre said:

If it's a cloud system why are you using RAID 10 with it?

I didn't build it.

Sure... Sure... Blame it on the other guys... If you can't fix it the easy way, at least you have a chance to redo it right. 🙂

http://community.spiceworks.com/topic/1122819-perform-ssd-over-provisioning-optimization-on-the-array-good-or-bad

It's RAID 100. See the post directly above yours 🙂