Speed comparison: comparing disk #, raid, CPU, encryption

[Spider99]

I only have a 431 here which isn't going to win awards for anything

The point you are completely missing is that the OP tests are applicable to your situation as done on QNAP and Synology hardware - with similar raid implementations showing real world results.

You are the one who has necro posted with you perspective but - no actual facts other than linking to old posts of other raid solutions - so its hard to understand why you have these views and harder to discuss without any facts to backup your belief that we have the wrong view.

You may be correct but your arguments are weak or non existent.

[a13antichrist]

Why would you want to retest the OP's results ? If you really want to .. invest some $$$ and test away

Because he only tested write performance whereas my claim is that read performance would show an advantage for R10. Besides, the whole point is that this thread is positioned to "refute the claim that R10 is faster than R5", which is just as misleading as the original "myth" that "R10 is faster". My only aim here was to point out that it is not as simple as "which is faster, which is slower", but that the context, usage, and characteristics of the arrays all play a role and there is no universal "faster" at all. Write Performance is not everything, and neither is Read Performance, and so it is disingenuous to test only one and then claim "the speed advantage is a myth".

That's all.

[a13antichrist]

On the other hand if you want change the title of this thread to:

"QNAP write-speed comparison over identical disk-count considering RAID level, CPU, Encryption."

then all power to you; I would fully support that, and at least it would be more representative and no-one could complain there was anything missing. Although I'd still take issue with the conclusion "so it's a myth that R10 is faster", which clearly over-simplifies the matter. Just don't try to rebuke a myth with more misleading (or incomplete, or over-inclusive) declarations.

[P3R]

I would trust professional thorough reviews far far greater above one user's anecdotal reports.

This thread describes a limited but well documented testing suite. It's okay to think that the OP have faked all these test results to decieve Qnap users (what on earth could the motive be for something like that?) but to openly suggest that by calling the results "anecdotal" without having done anything yourself but googling for tests that are all over the place only to spread FUD is really far below what I would expect from you.

What's really confusing is that now you're trying to discredit the validity of the tests, eventhough you previously said:

So, while the OP's numbers are not wrong, per se...

You can't really claim both that the tests are correct and incorrect if you want to have any credibility left in this forum so which is it now?

You finished the previous sentence with:

...the conclusion is faulty at best, and tending towards deception.

It's okay to call our conclusions wrong but then show us what's wrong with our conclusions. Also, results are results and the test is very clear about what's tested (a straight sequential write only taking as many other factors as possible out of the equation) so feel free to tell us your own conclusions from the testing.

Besides which, the OP is testing not just QNAP, so, that's invalid.

The tested NAS is from the other leading consumer NAS manufacturer, also using software RAID and the CPU is the same as in Qnap TS-X69 models. Also the test is very limited in testing specifically RAID performance only and doesn't use subsystems like networking, that would add confusion about specific hardware implementations of different manufacturers. Also, the same as with the RAID reliability calculator, you don't have to care at all about absolute numbers and a cross-platform comparison would be very pointless. So go ahead and make any relative comparisons of the performance numbers you want within the same platform.

If you want to you can even disregard the Syno test completely as it's an old and outdated hardware that haven't been marketed for several years. If we focus on the two other test suites it's a Qnap only test, with two Intel CPUs that's comparable in performance with many current low-end and high-end Intel-models respectively in what Qnap call their SMB segment.

Yes an 8-disk RAID 10 will be roughly 10 % faster than a 6-disk RAID and a 5-disk RAID 5. All giving the same amount of usable storage capacity.

The RAID 6 will be 97 times more reliable than the RAID 10 and the RAID 10 will be 20 times more reliable than the RAID 5 (according to https://www.servethehome.com/raid-calcu ... tdl-model/, using the same settings I posted in the other thread).

The cost however would be vastly different and unless using faster networking than wired gigabit, the real life performance difference experienced from clients wouldn't be noticeable as the networking is the bottleneck anyway. Of course the RAID 10 would be at it's maximum capacity (unless replacing all disks at huge cost) while both the RAID 5 and RAID 6 would have room for further expansion by adding disks and the RAID 5 could be migrated to a RAID 6. Both expansion and migration can be done while retaining data on the array during these migrations (backups are of course always recommended regardless).

Another limitation that we haven't touched on yet is that at least in the Qnap implementation, a RAID 10 group doesn't support any migration and even worse, can't be expanded by adding disks later (one could add additional storage to a storage pool but then not have any performance advantage from the added disks, which would negate any RAID 10 performance advantage). The latter is a huge limitation if starting out with a 4-disk RAID 10 configuration in a 6-disk, 8-disk or larger NAS model.

Given the above, RAID 10 looks pretty unattractive to home users (with mainly sequential usage) but that's just me and everyone is free to use what they want.

Eventhough you came out swinging here, in later posts you've proved to be both technically knowledgeable and actually listening to and understanding arguments in a to me impressive way. This post however was your all time low and in my opinion put you down in the group of all the other RAID 10 fans showing up here, when being pressured for arguments.

I sincerely hope that you'll stay and become a regular contributor in the forum and feel free to promote RAID 10. In busy professional environments (random access) I doubt anybody will even try to question your RAID 10 recommendation but for the large home user majority in this forum, you need to come up with better arguments to have a case.

[a13antichrist]

I never said the figures were wrong, in fact I even agreed that they are valid. I said the conclusions drawn were wrong, namely, misleading (to me, that means wrong), and that is the point that I have repeated. There is no black-&-white faster or slower, as a number of factors are involved. If the discussion is focussed on specific devices under specific conditions, then I agree, everything holds valid, but that is not stated meaningfully either in the title nor in the conclusion. In any case, nowhere have I said or given the indication that I wished to discredit the validity of the OP's results.

Also, I wouldn't consider myself a R-10 "fan". I would make the same cases/arguments for R-5 if someone was throwing unclear/imprecise facts in favour of R10. I do admire the --elegance-- of R10; however each has its role and purpose and I'm thankful for all of them.

[P3R]

On the other hand if you want change the title of this thread to:

"QNAP write-speed comparison over identical disk-count considering RAID level, CPU, Encryption."

The scope of the test is clearly stated in the first post and the title itself isn't making any claims at all about what's tested, the results or is in any other way misleading. In my opinion you're grasping at straws when requesting a change of title/subject.

Anyway, a change would be up to the OP to make himself. I would be very upset if a moderator/admin changed it without the consent of the OP, when it isn't as misleading as you try to claim.

Although I'd still take issue with the conclusion "so it's a myth that R10 is faster", which clearly over-simplifies the matter.

Please address me directly when your complaining about my posts. You did so initially here but I tried to focus the discussion to the other thread (that now on your request seems to have been moved here) where you also attacked me. I did so because it's very confusing to have parallell discussions on the same topic in different threads.

Indeed, in that and some other posts I have been oversimplifying the case, in exactly the same way RAID 10 fans had been oversimplifying the case for several years before this test showed up. For the first time there was testing done showing that RAID 5 and RAID 6 didn't s*ck as bad as these guys have stated over and over referring to the "write penalty". I knew my real life experience wasn't as bad as the RAID 10 bunch claimed it should be but I didn't have the hardware (or to be honest patience) myself to debunk the myth so forgive me for being excited when somebody finally presented this test.

What I also knew, different from most RAID 10 "experts" showing up in the forum over the years, are three things:

• The difference between random and sequential access.
• Home users usually have an overwhelming sequential usage.
• 90-95 % of forum participants are home users and the few professional storage admins present here doesn't have a need to ask the Qnap community for RAID-advice.

In any case, nowhere have I said or given the indication that I wished to discredit the validity of the OP's results.

You called the extensive testing opening this thread "anecdotal reports". Again, English isn't my first language so I looked the word "anecdotal" up to see if the meaning really was as bad as I thought. It was.

Feel free to think he didn't do the test you wanted to see and you may think my comments here where exaggerated (which they were) but that was a very low comment to make of the work the OP presented here!

I have since long asked other frequent contributors to not simply recommend RAID 5 in 4-bay models and RAID 6 in all larger NASes no matter what the circumstances. Actually I've had animated discussions on the subject with some of them.

Individual disk size, availability expectations, network infrastructure, number of concurrent users, monetary budget, type of usage, current and future storage demands are in my opinion all important factors to consider before giving RAID advice so I welcome everyone asking for things like that before making recommendations here. Please accept my challenge to become a more active contributor and try to improve the forum in the future instead of simply fighting my soon 3-year old post here.

[a13antichrist]

The scope of the test is clearly stated in the first post and the title itself isn't making any claims at all about what's tested, the results or is in any other way misleading. In my opinion you're grasping at straws when requesting a change of title/subject.

What "straws"? I don't have an agenda here - I just want to ensure that there is no misleading information.

Please address me directly when your complaining about my posts. You did so initially here but I tried to focus the discussion to the other thread (that now on your request seems to have been moved here) where you also attacked me.

From the beginning, my complaints have been - for the most part - about the conclusions drawn. When I called something misleading, I'm not --specifically calling out your posts. The comment about "myth" though did come from you.

Perhaps my original tone was a little aggressive. I'll grant you that, and for that you have my apologies. However your comment "that's the internet myth that so many are blinded by" does not really imply a specific focus on QNAP devices and/or limited-bay devices. By citing "the internet" you're literally making the claim as global as possible.

Indeed, in that and some other posts I have been oversimplifying the case, in exactly the same way RAID 10 fans had been oversimplifying the case for several years before this test showed up. For the first time there was testing done showing that RAID 5 and RAID 6 didn't s*ck as bad as these guys have stated over and over referring to the "write penalty". I knew my real life experience wasn't as bad as the RAID 10 bunch claimed it should be but I didn't have the hardware (or to be honest patience) myself to debunk the myth so forgive me for being excited when somebody finally presented this test.

Yes, exactly, and that's precisely why I think it's important that we disclose/state the --whole-- truth, and not introduce --more-- incomplete information.

You called the extensive testing opening this thread "anecdotal reports". Again, English isn't my first language so I looked the word "anecdotal" up to see if the meaning really was as bad as I thought. It was.

There is nothing "bad" with the word anecdotal. Anecdotal means, you heard something somewhere, and you relay it somewhere else in indefinite terms. If you were to go to another storage forum and claim "I know a guy who did tests and found that R5 was faster", that would be a very definition of an anecdote. Links & concrete data avoid that, but I imagine that many people read this thread, then go away thinking, "cool R5 is faster than R10", and any time they then report that info, that's anecdotal.

Feel free to think he didn't do the test you wanted to see and you may think my comments here where exaggerated (which they were) but that was a very low comment to make of the work the OP presented here!

He can do any test he likes. My objection, as it has been from the beginning, is the usage of "it's faster" without context or mitigating considerations.

Individual disk size, availability expectations, network infrastructure, number of concurrent users, monetary budget, type of usage, current and future storage demands are in my opinion all important factors to consider before giving RAID advice so I welcome everyone asking for things like that before making recommendations here. Please accept my challenge to become a more active contributor and try to improve the forum in the future instead of simply fighting my soon 3-year old post here.

I fully agree. And in the context of this forum, where RAID structures are primarily count-limited, the data is a valid, interesting analysis of write performance on consumer NAS devices. What it is --not-- is a general evaluation of RAID-level performance, and while I'm not claiming that was even the intended message, the resulting commentary was ambiguous and my only goal was to attempt to remove some of that ambiguity.

You know what, you guys asked for facts/data. Well, how about we take a closer look at the OP's own data...? Let's see what happens if we match capacity instead of spindle count.

To clarify:
4-disk RAID 10 = same capacity as 3-disk RAID 5; 4-disk in RAID 6
6-disk RAID 10 = same capacity as 4-disk RAID 5; 5-disk in RAID 6
8-disk RAID 10 = same capacity as 5-disk RAID 5; 6-disk in RAID 6

SO, let's see how that lines up. From the OP's own data:

1. NAS with 8 bays with Atom D2700 dual core @ 2.13 GHz (not a QNAP model, but that 'other' brand, wink wink, psst. the 1813+)
2. QNAP TS-870 with Celeron G550 dual core CPU @ 2.6 GHz
3. QNAP TS-870 with i7 3770t quad core CPU @ 2.5 GHz
4. Disks used (always using disk 1-n when testing with 'n' disks):
disk 1-4: Hitachi Deskstar 1TB 7200 rpm
disk 5-7: WD GREEN 1TB
disk 8: WD GREEN 2TB
5. Disable syncing (echo idle > /sys/block/md1/md/sync_action) -- avoid 10% performance hit
6. Disable thin provisioning -- avoid 15% performance hit

1. NAS with 8 bays with Atom D2700 dual core @ 2.13 GHz

3 disks in raid-5 72.11 MB/s 76.35 MB/s
4 disks in raid-6 113.6 MB/s 110.8 MB/s
4 disks in raid-10 155.2 MB/s 147.7 MB/s

4 disks in raid-5 167.1 MB/s 176.2 MB/s
5 disks in raid-6 154.8 MB/s 135.3 MB/s
6 disks in raid-10 227.4 MB/s 218.8 MB/s

5 disks in raid-5 210.5 MB/s 176.2 MB/s
6 disks in raid-6 175.8 MB/s 165.3 MB/s
8 disks in raid-10 238.9 MB/s 249.5 MB/s


2. QNAP TS-870 with Celeron G550 dual core CPU @ 2.6 GHz

3 disks in raid-5 135.3 MB/s 134.8 MB/s
4 disks in raid-6 133.9 MB/s 133.3 MB/s
4 disks in raid-10 147.2 MB/s 150.4 MB/s

4 disks in raid-5 202.1 MB/s 203.4 MB/s
5 disks in raid-6 207.8 MB/s 211.7 MB/s
6 disks in raid-10 229.3 MB/s 234.8 MB/s

5 disks in raid-5 275.4 MB/s 268.0 MB/s
6 disks in raid-6 270.1 MB/s 271.4 MB/s
8 disks in raid-10 295.2 MB/s 298.6 MB/s


3. QNAP TS-870 with i7 3770t quad core CPU @ 2.5 GHz

3 disks in raid-5 155.6 MB/s 156.1 MB/s
4 disks in raid-6 155.2 MB/s 159.5 MB/s crypted: 134.5 MB/s 127.9 MB/s
4 disks in raid-10 166.0 MB/s 159.4 MB/s

4 disks in raid-5 241.8 MB/s 230.9 MB/s
5 disks in raid-6 245.9 MB/s 221.9 MB/s crypted: 184.1 MB/s 189.1 MB/s
6 disks in raid-10 254.1 MB/s 257.4 MB/s

5 disks in raid-5 325.2 MB/s 316.5 MB/s
6 disks in raid-6 324.2 MB/s 315.8 MB/s
8 disks in raid-10 347.9] MB/s 316.2 MB/s

Summary: A constant and complete victory for RAID-10. Now, does that mean that RAID-10 is "simply faster"? No, of course not. In fact the OP even calls out a number of factors:

(1) when comparing RAID-5 and RAID-6:
RAID-5 and RAID-6 are comparable when you look at the same number of data disks (e.g. 2+1 in RAID-5 compares to 2+2 in RAID-6)

Yes, exactly - so, why not use the same rule with R10 in the first place? Not doing so is misleading.

(3) comparing CPU's:
(b) the G550 and i7 are much faster, both run out of steam beyond roughly 6 data disks in RAID-5 and RAID-6

(4) when considering RAID-10
The G550 and i7 CPU's are more than capable to perform the XOR operations at high speeds.

Indeed, the modern CPUs do a great job of neutralizing a lot of the dreaded "write penalty".

(4) when considering RAID-10 In the numbers you can see that RAID-10 only gives a slight advantage when running on the Atom CPU. Also, note that only write speeds where compared. The striping advantage of RAID-10 is only effective when reading.

This is misleading. Well actually, not misleading, it's just incorrect. The striping advantage comes into play for writing. It's the mirroring and the reading from both mirrors simultaneously that makes the [primary] difference for read results. XOR 'penalty' is of course also relevant, but less so with more powerful processors, as we've seen.

So it should be very clear to see that the "RAID-10 performance myth" is anything -but- a myth. You just have to have your context right.

Now, absolutely, as it pertains to limited-bay QNAP devices, this consideration may well be less valid. In the context of QNAP users, and this forum and their likely usages, the data presented here is relevant and of interest. But as has been made abundantly clear, there are many factors that influence the overall performance characteristics of the array, and so really the only thing that should --not-- be claimed here is that one RAID level is --necessarily-- ever faster than another, without giving the appropriate context. Which is exactly what I said from the start.

[Spider99]

Sorry - doing capacity comparisons means you are comparing more spindles with less - especially at the higher end 8 vs 5/6 - where 5 disk raid5 and 6 disk raid6 are almost the same speed as an 8 disk raid 10 - not a compelling argument that you need two or three extra spindles to get approximately similar speeds.

[a13antichrist]

Sure, if you want to arbitrarily stick your head in the sand, scream like a baby and say "no no no no R5 is always faster" then of course you can find metrics to support your claim. The fact is, there is a reason that R10 has an "assumed performance advantage" and that reason is, in professional circles capacity is the static metric, not disk count. As I've already said, in QNAP circles the focus may well be different, and that's perfectly fine. And it's hardly rocket-science either way that R5/R6 have write advantages at identical spindle counts, since (as I've mentioned before) only half the drives are effectively write-active whereas 2x the drives are read-active. So [as I've had to repeat, over and over and over] it depends entirely on your grounding metric. In QNAP circles, great, there is an argument to be made. Just don't claim that it's a universal truth and that you have somehow disproven a global myth.

Sorry - doing capacity comparisons means you are comparing more spindles with less - especially at the higher end 8 vs 5/6 - where 5 disk raid5 and 6 disk raid6 are almost the same speed as an 8 disk raid 10 - not a compelling argument that you need two or three extra spindles to get approximately similar speeds.

Write speeds. Try a read test someday. There is no universal metric.

[Spider99]

You are being silly now i have not said anything about what i "believe" - you are making things up now - because you cannot find a good argument to convince people one way or the other. I was pointing out a weakness in your argument that was obvious to me and not used by you to qualify your statements.

Try and step back and come up with some FACTS not your belief.

Being insulting just puts you in an even weaker position.

[a13antichrist]

It's not an argument when I started the post by stating it as my starting point. What do you even think I'm trying to convey here, have you even read anything I've said? I'm not a RAID-10 addict, I'm simply trying to make sure the full story is heard.

R5 is faster on writes at same spindle counts (makes perfect sense).

R10 is faster on writes at same capacity (makes perfect sense).

Ignoring the facts and continuing to bleat that "that's not fair" doens't help anyone.

[Spider99]

yes unfortunately i have read everything you have posted

You think you are correct - but have not conveyed any meaningful addition to the discussion - other than a few old posts and your assertions - as i have said before you are not going to convince me or others that your version is correct without adding facts that back this up.

You may be correct then again maybe not - it difficult to tell

You have been chippy with three senior members of this forum who have spent time trying to understand/discuss you position but you fail to get that we would probably agree with you IF you had something original to discuss - but alas you do not.

As you are so immature that you result to insults rather than a discussion kind of makes this whole effort as waste of time by us and you.

[a13antichrist]

Sooo as I've said multiple times, I guess I'll say it once more - I'm not trying to convince -anybody- of anything. I don't need nor want anybody to "agree with me". I'm providing contextual considerations, nothing more. The information is yours and everyone's to receive/consider/ignore as they please.

Actually - humour me for one second, won't you: What exactly -do- you think I am trying to prove?

[Spider99]

"Sorry but your/OP's original premise here is totally misguided.

"Number of Drives" is a stupid basis for comparison."

[a13antichrist]

"Sorry but your/OP's original premise here is totally misguided.

"Number of Drives" is a stupid basis for comparison."

And I have already acknowledged that in the context of QNAP devices, it does make sense as a comparison, since it's a limiting factor in purchase/configuration decisions. My warning was merely, "don't assume that proves any kind of rule about RAID levels in general".