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Tι εστι RAID ?


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Πιστεύω αυτό θα σου λύσει την απορία....

RAID, SCSI and Serial ATA RAID Info

RAID Glossary

The level of a RAID system (Redundant Array of Inexpensive Disks) relates to its operating mode and how the hard disks are combined to form a single logical drive.

RAID- 0

RAID Level 0 requires a minimum of 2 drives to implement

RAID 0 implements a striped disk array, the data is broken down into blocks and each block is written to a separate disk drive I/O performance is greatly improved by spreading the I/O load across many channels and drives Best performance is achieved when data is striped across multiple controllers with only one drive per controller This is of particular benefit for video editing and image editing programs. However, if one drive fails, you lose the data on all drives. blank.gif

RAID-1

For Highest performance, the controller must be able to perform two concurrent separate Reads per mirrored pair or two duplicate Writes per mirrored pair. RAID Level 1 requires a minimum of 2 drives to implement

RAID-1 (mirroring) involves mirroring the complete contents of one hard disk onto another. From the security standpoint, this is ideal (although not cheap), as the redundancy uses 50 percent of your hard disk capacity. There is a marginal increase in performance. Write access is slightly slower, but the controller uses the fastest available disk for reading data. Twice the Read transaction rate of single disks, same Write transaction rate as single disks. 100% redundancy of data means no rebuild is necessary in case of a disk failure, just a copy to the replacement disk. Transfer rate per block is equal to that of a single disk.

RAID-3

RAID-3 requires at least three hard disks, one of which is used to store error-correction data. Should a disk fail, the missing data can be restored from the parity and error-detection information on the redundant disk using an allocation algorithm. As RAID-3 interleaves the data across the drives, read speed is good, but writing is slower.

RAID-5

Each entire data block is written on a data disk; parity for blocks in the same rank is generated on Writes, recorded in a distributed location and checked on Reads. RAID Level 5 requires a minimum of 3 drives to implement

RAID-5 writes the original data and the error-correction information across all available drives (at least three). Writing is thus spread across all the drives in a RAID-5 system, which means that both reading and writing operations may overlap. RAID-5 offers good price/ performance, as only the space equivalent to one disk is allocated to the redundant data. Highest Read data transaction rate. Medium Write data transaction rate. Low ratio of ECC (Parity) disks to data disks means high efficiency

RAID 0+1

RAID Level 0+1 requires a minimum of 4 drives to implement.

RAID 0+1 is a combination of RAID level 0 and level 1. The disks are combined using the striping technique, and then mirrored. This only makes sense if speed is a priority, since two mirrored drives represent an expensive form of insurance. RAID 0+1 is implemented as a mirrored array whose segments are RAID 0 arrays. RAID 0+1 has the same fault tolerance as RAID level 5. RAID 0+1 has the same overhead for fault-tolerance as mirroring alone. High I/O rates are achieved thanks to multiple stripe segments. Excellent solution for sites that need high performance but are not concerned with achieving maximum reliability.

RAID 10

RAID Level 10 requires a minimum of 4 drives to implement.

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RAID 10 is implemented as a striped array whose segments are RAID 1 arrays. RAID 10 has the same fault tolerance as RAID level 1. RAID 10 has the same overhead for fault-tolerance as mirroring alone. High I/O rates are achieved by striping RAID 1 segments. Under certain circumstances, RAID 10 array can sustain multiple simultaneous drive failures. Excellent solution for sites that would have otherwise gone with RAID 1 but need some additional performance boost

http://www.gen-x-pc.com/more_raid.htm
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Nα'σαι καλα γιατρε!

Και κατι αλλο .

Με το ghost μπορω να παρω κανονικο image και των 2 σκληρων σε raid 0 ?

Με raid 0 ουσιαστικά αυτό που γίνεται είναι να κάνει image τον ένα σκληρό στον άλλο.Έτσι ουσιαστικά δεν θα χάσεις τα δεδομένα σου γιατί γίνονται backup σε 2 σκληρούς ταυτόχρονα.RAID 0 βάζουμε όταν θέλουμε να είμαστε σίγουροι ότι έχουμε σοβαρά δεδομένα και δεν θέλουμε να τα χάσουμε με τίποτα.Οι σκληροί που θα χρησιμοποιήσουμε πρέπει να είναι ίδιοι, και ο δεύτερος σκληρός, ουσιαστικά χρησιμοποιείται ΜΟΝΟ για το backup του πρώτου.Έτσι δηλαδή χάνουμε χώρο, αλλά κερδίζουμε σε ασφάλεια.
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Μηπως μπερδεψες το raid 0 με το raid 1 ή μου φαινεται?
Ε....ναι έχεις δίκιο, μπερδεύτηκα :086:

Πάντως μπορείς να πάρεις κανονικά backup τα δεδομένα.

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Mπορω να κανω partition με το partition magic σε raid 0?

Θα ενδιαφερε παρα πολυ η ταχυτητα που προσφερει το raid 0 αλλα θελω να εχω ξεχωριστα partitions για παχνιδια κτλ. Και αυτο γιατι οταν κανω image το σκληρο μου δεν θελω να γραφω καμμια 10αρια dvdακια με οχι τοσο αναγκαια πραγματα. Θελω να κανω backup με το ghost το partition με τα winxp και τις εφαρμογες τους και οχι τα αλλα

partitions.

Γινεται λοιπον να κανω partitions σε raid 0?

ΥΓ Δηλαδη με raid 0 τα win βλεπουν τους 2 σκληρους σαν εναν ,σωστα?

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Eχω μεινει κομματακι πισω σε αυτο το θεμα...

Τι εστι RAID ? :100:

Αν δεν απατωμαι υπαρχει RAID 0 και RAID 1 ... :100:

Καλο θα ηταν να διαβαζαμε τα stickies λιγες σειρες πιο πανω ... ;)

Διαβασε τα ποστ του Ερμουλη περιπου στη μεση

http://www.pctechnology.gr/vbull/vb/showthread.php?t=143

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  • 3 weeks later...
ΝΑ ρωτήσω και εγώ κάτι. Το raid γίνεται μόνο σε sata ή και σε udma?
Aν έχεις τον καταλληλο controller, γίνεται και στα δύο.
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  • 2 months later...
έχω μια msi k7n2delta - ilsr και έχει raid εγώ θέλω να κάνω mirroring και stripping γίνετε και τα 2 μαζί?

Αν όχι πως μπορώ να έχω την ποιο γρηγορη ταχύτητα πάνω στα raid?

Αυτο που λες ειναι το raid1+0... Xρειαζονται 4 δισκοι . Δυο που γινονται raid0 , και αυτοι γινονται mirror (raid1) πανω σε αλλους δυο .

Για ταχυτητα πας σε raid0 (striping) .

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RAID 5: Why And For Whom?

Unlike the now well-established RAID levels 0 and 1, which offer either faster performance or increased security in the event of hard disk failure, RAID 5 offers both performance and security benefits. RAID 5 needs some powerful logic processing capabilities to control the simultaneous operation of several hard disks and to write data and parity information across all disks in the stripe set. The latter function does not require a particularly complex architecture, but as transfer rates increase, the process of writing parity data on the fly increases CPU overhead accordingly.

We must differentiate here between software RAID, as employed by HighPoint, and hardware RAID, in which a RISC processor carries out all processor-intensive operations. Promise has included its own XOR processor in its controller; Adaptec, ICP and LSI Logic prefer to rely on tried and true chips from Intel.

To write data and parity blocks across all the drives in the array, a RAID 5 setup requires a minimum of three hard drives. The "wasted" disk space in this case would be 33%, which is still rather high. The space required to store parity information decreases as the number of drives is increased, although the risk of drive failure is increased. The worst-case scenario is, of course, when two hard disks fail at the same time.

We can draw the following conclusions from the above: With four drives, you "sacrifice" ¼ of the available storage space, while maintaining a low likelihood of the worst-case scenario taking place. And a four-drive RAID 5 array is not restricted by the performance limits of the PCI bus with its 133 Mbps (32-bit, 33 MHz).

It is worth mentioning here that a RAID 5 array is hardly ever a viable solution for a desktop PC. Even with workstations, RAID 0+1 (striping + mirroring) or RAID 10 (mirroring + striping) remain the superior and fastest solutions, even though they utilize more of your available hard disk capacity.

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Quote:

Originally Posted by Dark_Emperor

έχω μια msi k7n2delta - ilsr και έχει raid εγώ θέλω να κάνω mirroring και stripping γίνετε και τα 2 μαζί?

Αν όχι πως μπορώ να έχω την ποιο γρηγορη ταχύτητα πάνω στα raid?

Αυτο που λες ειναι το raid1+0... Xρειαζονται 4 δισκοι . Δυο που γινονται raid0 , και αυτοι γινονται mirror (raid1) πανω σε αλλους δυο .

Για ταχυτητα πας σε raid0 (striping) .

βέβαια μπορεί να κάνει και matrix raid με δύο σκληρούς δίσκους μόνο εκμεταλεύοντας raid 1 και raid 0 (κάνοντας partitioning) αν βέβαια το υποστηρίζει η μητρική

info: http://www.tomshardware.com/motherboard/20040619/socket_775-30.html

Αυτο είναι μαγκία της Intel και προφανώς δέν το υποστηρίζει η δικιά σου μητρική dark emperor (msi k7n2delta - ilsr) αφου είναι για amd... :019:

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Το raid5 γινεται ειναι αψογο , αλλα συνηθιζεται σε SCSI . Υπαρχουν και καποιες υλοποιησεις σε SATA βεβαια

Το matrix raid απαιτει μητρικη με chipset i9x5 ... γι'αυτο και δεν εκανα αναφορα σε αυτα. Βεβαια , καλυτερο το 0+1 . Αν θελω ταχυτητα και ασφαλεια για το λειτουργικο μου , απλα το matrix δεν μου κανει .

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Αν θελω ταχυτητα και ασφαλεια για το λειτουργικο μου , απλα το matrix δεν μου κανει .

it finally fuses the performance advantage of a RAID 0 array with the data safety that only a RAID 1 array is able to provide - but with using two drives only!

άρα δέν είναι ούτε αργό , ούτε ανασφαλές....

Βέβαια, If you wanted to get a faster drive subsystem and simultaneously increase fault tolerance, you would have to go for a four-drive RAID 0+1 array, which of course is expensive. :045:

γιαυτό δέν πρέπει να απορίπτεται έτσι έυκολα η λύση matrix raid (πόσο μάλλον απο Intelάδες σάν και εσένα) :D

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it finally fuses the performance advantage of a RAID 0 array with the data safety that only a RAID 1 array is able to provide - but with using two drives only!

άρα δέν είναι ούτε αργό , ούτε ανασφαλές....

Βέβαια, If you wanted to get a faster drive subsystem and simultaneously increase fault tolerance, you would have to go for a four-drive RAID 0+1 array, which of course is expensive. :045:

γιαυτό δέν πρέπει να απορίπτεται έτσι έυκολα η λύση matrix raid (πόσο μάλλον απο Intelάδες σάν και εσένα) :D

Μα το εχεις κανει quote ! To 0+1 ειναι πιο γρηγορο και πιο ασφαλες ! :D

Χιλλιες φορες να μας εδινε ενα raid5 .... παρα το matrix .:006:

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