Are the posted questions getting worse?
- Lynn Pettis - Monday, August 20, 2018 1:41 PM
If you had ever looked at the the geekstuff.com's page on RAID01 vs RAID10 seeing nonsense about RAID wouldn't come as a surprise. Some of the errors in the original article have been corrected (but it still says RAID01 can have 3 discs although since the 0 in 01 says stripe length > 1 and the 1 in 01 says 2 stripes there must be at least 4 discs in RAID01). I've never seen the 3 disc RAID01 claim except on that page.
But the craziest stuff isn't in the aricle, it's in the comments. There are calculations done assuming that if N events each have probability p the chance of at least one occurring is Np (instead of 1-(1-p)^N), and incorrect replies to those comments, and comments that claim to prove that RAID01 is as reliable as RAID10 (by assuming that RAID 01 handling of broken discs is identical to RAID 10 handling of broken discs). I haven't read all the comments, but from what I have read I imagine that if there's anything completely silly that can be said about RAID01 it can probably be found in that page's comments.Tom
- TomThomson - Tuesday, August 21, 2018 5:44 AM
Wikipedia also claims that RAID01 can be 3 discs, but only in the accompanying picture: https://en.wikipedia.org/wiki/Nested_RAID_levels#RAID_01_(RAID_0+1).
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk - Thom A - Tuesday, August 21, 2018 5:50 AM
I don't even want to contemplate what would be involved in setting up that sort of an array...
Give me a nice, normal, 4-disk RAID0+1 or 1+0 any day. - Thom A - Tuesday, August 21, 2018 5:50 AM
Well, the diagram loooks more like RAID 1E than any sort of RAID01.
And the wikipedia page does say that RAID01 provides the same space as does RAID1 with the same number of discs. Unlike RAID 1E, requires an even number of discs, which rules out 3..
Besides, RAID01 has a slice length greater than 1 disc (that's the 0) and the slice is duplicated (that's the 1). So the possible number of discs for RAOD01 is an even number greater than 2 so it's at least 4.Tom
- jasona.work - Tuesday, August 21, 2018 9:30 AM
I don't fancy setting it up like that either. But I think RAID01 arrays are unacceptable for many purposes because the potential down-time is too greatand that RAID 1E is a viable alternative to RAID 10, and in fact it has some advantages the ability to do it on an odd number of discs, and better performance than a RAID10 using the same number of discs while waiting for a replacement disc, and while populating the replacement disc once it has arrived, and I guess if I needed those advantages I would put up with the effort of setting it up assuming I could have a RAID controller that supported RAID 1E.
At Neos I insisted that all servers delivered to customers should use RAID10. No other RAID configurations permitted. If RAID 1E had been available back then I would have allowed it, possibly even recommeded it for big systems after doing some performance measurement and making sure that our custmer support and delivery people could handle it (including setting it up). But I didn't hear of RAID 1E until many years later.
Tom
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Talk to me about perfection when we can compute pi exactly (in anything other than Base pi). Reality is fuzzy 😉
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Against stupidity the gods themselves contend in vain. -- Friedrich Schiller
Stop, children, what's that sound? Everybody look what's going down. -- Stephen Stills - The Dixie Flatline - Tuesday, August 21, 2018 1:55 PM
Looks exact to me, albeit a transient computation
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Looks tasty, if imperfect, to me, Steve. Needs a big scoop of vanilla bean ice cream to go with. 🙂
__________________________________________________
Against stupidity the gods themselves contend in vain. -- Friedrich Schiller
Stop, children, what's that sound? Everybody look what's going down. -- Stephen Stills - The Dixie Flatline - Thursday, August 23, 2018 12:28 PM
Agreed. It would be beautiful if the ice cream were a perfect sphere.
- Ed Wagner - Thursday, August 23, 2018 12:59 PM
Like it would last long enough us to notice. And keep your ice cream on your plate. Not on my pi pie
- Steve Jones - SSC Editor - Thursday, August 23, 2018 5:08 PM
Needs a shot of Drambui on the ice cream, wherever you put it.
--Jeff Moden
RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.Change is inevitable... Change for the better is not.
Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally) -
Ah, only 10 more work hours until I start my vacation...
Well, 7 hours today and 3 hours tomorrow...Going to lock up my work phone and laptop and leave them behind...
And, just to really enjoy myself, I'm going to follow my bosses instructions from yesterday to perform a test to see which of our customers are OK with the disaster recovery plan (basically, if our site gets closed for something, we're not obligated to get our systems back up until *after* the site is back up) by shutting down the production SQL. Which I'm going to do Saturday after I'm done patching and just before I turn off my phone and laptop.
(No I'm not doing this actually, he was joking and so am I.) -
How can you "forget" that you posted a question on a topic two weeks ago and still be able to function in a job that requires holding a lot of information in your head? How can you (presumably) implement something from that previous post and then "forget" that you had implemented it? https://www.sqlservercentral.com/Forums/1991420/Executing-same-SQL-code-twice
Drew
J. Drew Allen
Business Intelligence Analyst
Philadelphia, PA - drew.allen - Friday, August 24, 2018 8:35 AM
Because some of the people that are fulfilling these roles are terrifying people. I saw a topic the other day (not here), where someone had said they had hired to "rescue" and upgrade a database to MySQL SQL Server, however, they weren't sure how to start. If they were hired for that role why do they not know that MySQL and SQL Server are different RDBMS, and why do they not know where to start? It's honestly no wonder why I don't question some of the horror stories you read about IT disasters; tehre really are people that are in highly technical roles with no idea of the impacts of their actions (or what their actions should be).
I'm sure you consultants out there though love those kind of environments. 😀
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk - jasona.work - Friday, August 24, 2018 6:04 AM
Good for you. Enjoy the time off
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