Tuesday, August 3, 2010

RAID 60


The diagram in Figure A gives you an idea of how a RAID 60 array is constructed. Like RAID 50, RAID 60 is a multi-level disk set; you start with a bunch of RAID 6 sets, and then these sets are aggregated at a higher level into a RAID 0 array that has no redundancy on its own. However, each RAID 60 set does have redundancy and can withstand the loss of up to two disks in each parity set. In theory, in the diagram below, you could lose six of the 12 total disks (two in each set) and still have an operational array. As soon as you lose more than two disks in a single parity set, though, your world would come crashing down, as the RAID 0 set breaks, and you’re back to data recovery mode.
Figure A
RAID 60 diagram
An additional note: RAID 60 requires a minimum of eight disks in order to operate — you need at least two four disk RAID 6 sets to comprise a single RAID 60 set.

RAID 60 benefits and drawbacks

I like RAID 50 a lot, so you might think that I’m a big believer in taking that to the next level and that I would like RAID 60 even more; to be honest, I’m not sure. I see RAID 50 as a great balance between capacity, performance, and reliability, and I see RAID 60 as potentially imbalanced on the capacity side (to the negative) in order to support the increased reliability inherent in RAID 60.
I don’t think you should simply avoid RAID 60 at all costs; instead, make the decision on a case by case basis with an understanding of the tradeoffs that you’ll face. In fact, you might find that RAID 60 is a great fit when you need higher usable capacity and better reliability and can trade a little in write performance for it.
With RAID 60, you’re going to lose anywhere from around 12% to 50% of your usable space to parity information. This is not a bad thing, and the whole design of RAID 6 is built around the idea that using more space (two disk’s worth to be exact) to enhance reliability is a good thing. If you’re ultra-concerned about reliability, are you more likely to use fewer disks per individual RAID 6 set? If so, this would decrease the overall usable capacity of the solution. In fact, in the diagram above, you’d lose 50% of your disk space to parity, so why not just go with RAID 10 in that scenario?
With RAID 6, you will take a performance hit (more so than with RAID 50) when it comes to writes, but reads will be boosted, as is the case with RAID 10 and RAID 50. The exact performance hit you take with writes under RAID 60 is largely dependent on the quality of your RAID controller and on what you’re doing. If you’re considering implementing a RAID 60 that eats 50% of your space in overhead, it’s time to consider just using RAID 10, which will provide similar read performance and better overall write performance and provide similar levels of redundancy.
From a pure reliability perspective, a RAID 60 array is orders of magnitude more reliable than even RAID 50 arrays due largely to the extra parity disk employed in RAID 60.
The more disks you add to each individual RAID 6 set in a RAID 60 array, the higher percentage of usable space you get from the overall RAID 60 array. Perhaps the biggest tradeoff in RAID 60 is that you can build larger individual RAID 60 sets in a safer manner than is possible under RAID 50, so from that perspective, perhaps you can get more safely usable space from a RAID 60 array.

Conclusion

When it comes to RAID 60, I don’t think IT pros should have a one-size-fits-all mentality. And before you jump on the RAID 60 train, be aware that there are potential downsides for usable space and performance that need to be considered, so choose wisely.

RAID 50


RAID 50 is an often overlooked RAID level that can bridge the gap when it comes to choosing between RAID 5, RAID 6, and RAID 10. Scott Lowe explains why he likes RAID 50.
———————————————————————————————————
RAID 50 is my favorite RAID level. Although RAID 50 support is not in every product (for example, my EMC AX4 at Westminster College does not support RAID 50), I find that RAID 50 provides a great balance between storage performance, storage capacity, and data integrity that’s not necessarily found in other RAID levels.
If you haven’t used RAID 50 before, you’re in for a treat. As one of the many multilevel RAID options that are out there, RAID 50 operates by striping (RAID 0) data across multiple RAID 5 sets (Figure A).
Figure A
raid50
RAID 50 diagram
As you can see in the diagram, there are three RAID 5 sets that span a total of 12 disks. Each RAID 5 set has four disks, with one disk’s worth of capacity dedicated to parity information. For the example above, this means that each RAID set will lose 25% of its total capacity to parity information, as would be the case if you were to deploy a single four-disk RAID 5 set. The beauty of RAID 50 lies in the “0″ part of the RAID level; this is where information is striped across each of those underlying individual RAID 5 sets.
There are a number of reasons why I like RAID 50, but there are also tradeoffs to using this RAID level. Here are some pros and cons about using RAID 50.

Disk space

RAID 5 requires 1/#disks worth of space per RAID array. In Figure A, this would mean that, if all 12 disks were in a single RAID 5 set, you’d be left with 11 disks worth of capacity. With RAID 50, you need to allocate one disk per underlying array for parity, so you’re left with less usable space than you would have if you simply used RAID 5.
However, if you compare RAID 50 and RAID 10, you’ll see a clear winner in RAID 50 from a capacity perspective. With RAID 10, you always lose 50% of your capacity due to mirroring. Since each underlying RAID 5 array requires a minimum of three disks (RAID 5 rules), and you lose the capacity of one disk to parity, you’ll never “lose” more than 33% of your total capacity when using RAID 5. As you make each RAID 5 set larger, this loss percentage goes down. In Figure A, with four disks used in each RAID 5 set, 25% of capacity is used for parity overhead; if you make that five disks per RAID 5 set, this percentage drops to 20%. As this percentage drops, your risk increases.
RAID 50 requires an array with at least six disks — two RAID 5 arrays of three disks each. I like to use three or four disk RAID 5 sets in RAID 50 arrays.

Risk

With RAID 5, as you increase the number of disks in the array, you increase the likelihood that you’ll experience total array failure as more than one drive fails at the same time. As you move into RAID 50 territory, that additional disk space that you’re giving up translates directly into lowered risk, as RAID 50 systems can suffer multiple disk faults — as long as those disk faults happen in the right places.
With RAID 50, if you suffer multiple disk faults in any of the underlying RAID 5 arrays, the entire RAID 50 is toast; however, each individual RAID 5 array can withstand the loss of a single disk. You never want to have more than one disk go bad at a time regardless of RAID configuration, but at least with RAID 50, your chances are much better that a second disk failure will not happen in the same array as the first failure. This is one reason that keeping the individual RAID 5 arrays small (three or four disks at most) makes a lot of sense. The more disks you add to the individual RAID 5 arrays, the higher your risk for suffering a dual disk loss in one array.
Remember, the “0″ part of RAID 50 offers no fault tolerance; all fault tolerance happens at the individual RAID 5 level. The RAID 0 part does help with performance.

Performance

RAID 50 does not perform as well as RAID 10 when it comes to performance in a degraded state (i.e., during a rebuild), but RAID 50, at least theoretically, performs much better than RAID 5 in overall write performance; this places RAID 50 between RAID 10 (the winner in performance) and RAID 5 (sometimes lackluster performance, depending on workload) in the performance spectrum. Actual performance usually depends on the choice of RAID controller and the kind of information being processed.
Like RAID 10 and RAID 5, RAID 50 provides excellent read performance.

Summary

When it comes to achieving a balance between storage cost, risk, and performance, few RAID levels go as far as RAID 50 for the following reasons:
  • Storage. Although RAID 50 uses more overhead space than RAID 5, it requires much less overhead than RAID 10, making it a nice in between choice.
  • Risk. With RAID 5 alone, organizations run the risk of a second disk failure that could compromise the entire array. RAID 50 mitigates this issue since multiple disks can fail, as long as the disks are the right ones.
  • Performance. Although overall read/write performance is highly dependent on a number of factors, RAID 50 should provide better write performance than RAID 5 alone.

How to Say Common Phrases in Multiple Languages


Thank You

  • Bengali: ধন্যবাদ (Dhon-no-baad)
  • Dutch: Dank u (formal)or Dank je
  • French: Merci.
  • German: Formal. Vielen Dank. Informal: Danke.
  • Portuguese: Obrigado (male)/obrigada(female).
  • Spanish: Gracias.
  • Tagalog/Filipino: Maraming salamat.
  • Korean:고맙습니다 (Koh-mahp-soom-ni-da)
  • Krio: Tenki
  • Mandarin Chinese: 谢谢 (Shyieh, Shyieh)
  • Swedish: Tack
  • Latin: Gratias ago.
  • Norwegian: Takk/Tusen takk/Takk skal du ha
  • Russian: Спасибо (spa-SI-ba)
  • Japanese: Formal: Domo arigato. Informal: Arigato.
  • Persian:متشکرم(moteshakkeram)
  • Telugu: ధన్యవాదాలు (dhan-ya-vaadhalu))
  • Serbian: Hvala
  • Urdu: Shukriya (Thankyou is also very common)
  • Finnish: Kiitos.
  • Malayalam: നന്ദി
  • Romanian: Formal: Multumesc Informal: Mersi
  • Korean: Kam-Sam-Ni-Da
  • Malay: Terima kasih

You're Welcome

  • Bengali: ঠিক আছে (thik aase)
  • Dutch: Graag gedaan.
  • French: De rien
  • French: Je vous en prie. (formal)
  • German: Formal: Gerngeschehen Informal: Bitte
  • Krio: Fo natin
  • Norwegian: Vær så god/Skulle bare mangle
  • Portuguese: De nada
  • Spanish: De nada
  • Russian: Пожалуйста (Pazhalusta)
  • Tagalog/Filipino: Walang anuman.
  • Korean: 천만에요 (Jeon-man-eyo)
  • Mandarin Chinese: 气 (Bu Kuh Chee)
  • Swedish: Var så god
  • Persian:خواهش میکنم(xaahesh mikonam)
  • Urdu: Khush Amadeed
  • Finnish: Ole hyvä.
  • Romanian: Cu placere
  • Japanese: Doo itashimashite.
  • Malay: Sama-sama

Where is it?

  • Bengali: এটা কোথায়? (eeta ko thay?)
  • Dutch: Waar is het?
  • French: Où est-il ?
  • German: Wo ist es?
  • Krio: Na weh ee be?
  • Norwegian: Hvor er det?
  • Tagalog/Filipino: 'Asan na 'yon? or Nasaan na iyon?
  • Spanish: ¿Donde está?
  • Russian: Где это? (Gdye eta?)
  • Mandarin Chinese: 哪儿 (Nar Yowe)
  • Swedish: Var är det?
  • Latin: Ubi id est?
  • Telugu: ఎక్కడ (yekkada)
  • Urdu: Kahan Hai Wo
  • Finnish: Missä se on?
  • Romanian: Unde este?
  • Japanese: Doko desu ka?
  • Malay: Dimanakah ia?

What did you say?

  • Bengali: আপনি কি বললেন? (aap ni ki bol len?) or simply (ki bol len?)
  • Dutch: "Wat zegt u?" or "Kunt u dat herhalen?"
  • French: Qu'est-ce que vous avez dit? Or simply Pardon?
  • German: Was haben Sie gesagt?
  • Krio: Wetin yu say?
  • Portuguese: O que você disse?
  • Spanish: Repite, por favor.
  • Tagalog/Filipino: Ano'ng sinabi mo? or Ano yung sinabi mo?
  • Mandarin Chinese: 你说什么? (Ni Shuo Le Shen Me?)
  • Norwegian: Hva sa du?
  • Swedish: Vad sa du?
  • Latin: Quid dixisti?
  • Russian: Что ты сказал? (Chto ti skazal?)
  • Serbian: та сте рекли?
  • Persian:چی فرمودید؟(chi farmudid?)
  • Telugu: ఏంటి (yenti)
  • Urdu: App nay kia kaha
  • Finnish: Mitä sanoitte?
  • Romanian: Ce ati/ai spus?
  • Japanese: Nan to ii mashita ka?
  • Malay: Apa yang telah kamu katakan?

You can sit down

  • Bengali: আপনি বসতে পারেন । (aap ni bosh-tey pa ren)
  • Dutch: U kunt gaan zitten.
  • French: Vous pouvez vous asseoir.
  • German: Sie können sich hinsetzen.
  • Krio: Yu kin sidom
  • Norwegian: (Polite: Vær så snill å...)Sett deg ned
  • Spanish: Puedes sentarte. (or, formally: puede sentarse)
  • Tagalog/Filipino: Maari kang maupo or Maupo ka.
  • Portuguese: Você pode se sentar.
  • Swedish: Slå dig ner.
  • Latin: Sedeas.(You may sit.)/Sedeas si placeas.(You may sit if you please.)
  • Persian:میتوانید بنشینید(mitavaanid beneshinid)
  • Urdu:App Baith saktaiy hain
  • Russian: Вы можете сесть. (Vi mazhyetye sest)
  • Finnish: Voit istuutua.
  • Romanian: Puteti/poti sa luati/iei loc
  • Telugu: koorchondi
  • Japanese: Dozo o kake kudasai.
  • Malay: Awak boleh duduk.

I love you

  • Bengali: আমি তোমাকে ভালোবাসি (aami to-ma-key valou bashi) Informal
  • Dutch: Ik houd van je(formal) or Ik hou van je
  • French: Je t'aime. Je t'adore.
  • German: Ich liebe dich.
  • Chinese(Mandarin): Wo ai ni.
  • Krio: ah lek you bad bad wan
  • Portuguese: Eu te amo.
  • Norwegian: Jeg elsker deg. (to a spouse/girlfriend/boyfriend) Jeg er glad i deg. (to family/friends)
  • Spanish: Te quiero. (to friend/boyfriend/girlfriend) Te amo (to family/spouse)
  • Latin: Te amo.
  • Tagalog/Filipino: Mahal kita or Iniibig kita.
  • Mandarin Chinese: 爱你 (Wo I nee)
  • Swedish: Jag älskar dig.
  • Japanese: Aishiteru.
  • Russian: Я тебя люблю. (Ya tebya lyublyu)
  • Persian:دوستت دارم(dustat daaram)
  • Telugu: నేను నిన్ను ప్రేమిస్తున్నాను (nenu ninnu premistunnanu)
  • Urdu: Main Ap say mohabut Karta hoon (Infact "I love You" is more common than this)
  • Finnish: Rakastan sinua.
  • Romanian: Te iubesc!
  • Korean: Sah-dang-ay
  • Malay: Saya cintakan awak

I'd Like That

  • Bengali: আমি ওটা চাই (aami ota chai)
  • Dutch: Dat lijkt me leuk/lekker ('lekker' is used for food, 'leuk' means 'nice' or 'fun'.
  • French: Je voudrais ceci.
  • German: Das gefaellt mir.
  • Norwegian: Det hadde vært hyggelig.
  • Spanish: Me gustaria eso
  • Tagalog/Filipino: Gusto ko iyan.
  • Mandarin Chinese: 欢它 (Wo Shee Hwan Ta)
  • Swedish: Jag gillar det
  • Latin: Illud velim./Illud vellissem.
  • Urdu: Mujhay woh pasand aiay ga
  • Romanian: Mi-ar placea asta
  • Japanese: Sore ga hoshii des. Suki desu.(I like it)
  • Malay: Saya memang sukakan itu.

Nice seeing you

  • Bengali: তোমাকে দেখে খুশি হলাম (toma-key dey-khey khu-shi holam)
  • Dutch: Het was leuk om je/u te zien.
  • French: Je suis content(e) de vous voir.
  • German: Es war nett, Sie zu sehen.
  • Krio: good fo watch yu (pronounced waach)
  • Norwegian: Hyggelig å møte deg/Hyggelig å se deg
  • Spanish: Encantado(/a if you are female, 'I am thrilled to meet you) a conocerte(/se if you want to be formal). /Mucho gusto
  • Tagalog/Filipino: Masaya ako na nakita ka.
  • Swedish: Trevligt att träffas.
  • Latin: Te spectare gaudeo.
  • Persian:از ملاقات شما خوشحال شدم(az molaaghate shomaa xosh haal shodam)
  • Urdu: App say mil kar acha laga
  • Finnish: Oli kiva tavata.
  • Romanian: Incantat/a sa va vad
  • Japanese: Yokoso. /Hisashi buri (It's been a long time)/Hajimemashite, yoroshiku onegai shimasu. (It is our first time. Let us be cordial with each other. Said when you meet the first time.)
  • Malay: Gembira bertemu dengan awak.

How are you?

  • Bengali: কেমন আছেন? (kemon aasen? formal) or কেমন আছো? (kemon aaso? informal)
  • Dutch: Hoe gaat met jou/u ( 'u' is the formal way) ?
  • French: Comment allez-vous ? Or: Ça va?
  • German: Wie geht es dir? (formal)
  • German: Wie geht's? (informal)
  • Krio: How yu do? (how pronounced ow)
  • Norwegian: Hvordan går det/Hvordan har du det?
  • Portuguese: Como vai você?
  • Spanish: ¿Como estás? (informal) ¿Como está Usted? (formal) ¿Que tal? (informal)
  • Tagalog/Filipino: Kumusta ka? (not Kamusta ka)
  • Korean: 안녕하십니까 (anneyong hasimnikka)
  • Mandarin Chinese: 你好吗 (Nee How Ma)
  • Swedish: Hur mår du? / Hur är det?
  • Latin: Ut vales.(Are you fine?)
  • Russian: Как дела? (Kak dyela? Informal)
  • Persian:حال شما چطور است؟(haale shomaa chetor ast?)
  • Urdu: Ap ka kia haal hai
  • Finnish: Mitä kuuluu? / Kuinka voit?
  • Romanian: Cine esti?
  • Telugu: Meeru yela vunnaru?
  • Japanese: Genki desu ka? (Are you fine?)
  • Malay: Apa khabar?

Sorry

  • Bengali: দুঃখিত (duk-khi-tow)
  • Spanish: Lo siento
  • French: Je suis désolé(e)
  • German: Es tut mir Leid
  • Tagalog/Filipino: Patawad,Paumanhin
  • Krio'': ah sorri oh
  • Korean: 미안합니다 Mi-an-ham-nida (formal) Mi-an-ay (Casual)
  • Norwegian: Unnskyld
  • Portuguese: Desculpe
  • Polish: Przepraszam
  • Chinese: 对不 (dwee boo chee)
  • Swedish: Förlåt
  • Latin: Mihi paenitet.
  • Russian: Извините (Eezveehitye)
  • Persian:متاسفم(mote?assefam)
  • Telugu: క్షమించండి (ksha-minchandi)
  • Urdu: Sorry (same)
  • Finnish: Anteeksi.
  • Romanian: Imi pare rau
  • Japanese: Gomen nasai OR sumimasen
  • Malay: Minta maaf.

I am fine/not good.(response to how are you)

  • Bengali: আমি ভালো আছি (aami valo acchi) fine / আমি ভালো নেই (aami valo nei) not good.
  • Chinese: 很好/坏 (Wo Hen Hao/Bu) *bu= bad, hao= good*
  • German: Es geht mir gut/schlecht
  • French: Je suis bien/mal.*bien=good *mal=bad *comme ci, comme ça=so, so
                           *très bien=really well *très mal=really bad
  • Krio'': ah no well/ gud
  • Norwegian: Det går ----- *bra=good *greit=ok *ikke så bra=dårlig
  • Spanish: Estoy bien/mal. *bien=good, mal=bad*
  • Latin: Bene/Male sum.
  • Urdu: Theek
  • Romanian: Sint...
  • Swedish: Iam fine: Jag mar bra *bra=good
  • Telugu : Iam fine : Nenu baagunnaanu *baagunnanu=fine
  • Japanese: I am fine: Hai, genki desu. / I am very fine: Genki ippai desu. / I am not fine(informal): Yoku nai. I am not fine(formal): Yoku arimasen.
  • Malay: I am fine: Saya sihat / I am not fine: Saya tidak sihat