想買千多元數的RAID 卡行RAID5

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發表於 2015-4-14 10:27 | 只看該作者

回覆 Dull
其實同明唔明無關係，我只係想講，你看電視機的話要知電視機的顯像原理????我在意的是速 ...
inone2 發表於 2015-4-14 10:04

1. 高階RAID卡唔係用I7, 係用RISC with hardware parity acceleration.
1.2GHz RISC 計parity 可以快過4GHz i7

2. COPY一隻4TB最多3個鐘
如果一隻HD seq write 有200MB/s
3個鐘: 200MB * 3600 * 3/1024 = 2.1TB

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monsterz

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72^#

發表於 2015-4-14 10:34 | 只看該作者

回覆 69# inone2

在rebuild過程中, CHing對XOR運算複雜度同RAID5磁碟數之相關性的考慮, 是有一定道理, 可惜此運算對CPU負擔並非你想像中那麼大.

小的用linux mdadm rebuild 5碟RAID5 (2TB per disk ST2000DL003), 10碟RAID5 (2TB per disk, WD GREEN), avg. CPU% 僅5% vs.15%, rebuild用時均為5~6小時, 相差不過10分鐘.

小的CPU為Celeron 1037U, 2 core, 1.8GHz. 5碟時全原生SATA2, 12碟時原生SATA2 X6 + 88SE9230 SATA3 X4

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t1066

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73^#

發表於 2015-4-14 12:30 | 只看該作者

回覆 70# inone2
抄咗一段英文wiki http://en.wikipedia.org/wiki/ZFS:

Software RAID using ZFS

ZFS offers software RAID through its RAID-Z and mirroring organization schemes.

RAID-Z is a data/parity distribution scheme like RAID-5, but uses dynamic stripe width: every block is its own RAID stripe, regardless of blocksize, resulting in every RAID-Z write being a full-stripe write. This, when combined with the copy-on-write transactional semantics of ZFS, eliminates the write hole error. RAID-Z is also faster than traditional RAID 5 because it does not need to perform the usual read-modify-write sequence.

As all stripes are of different sizes, RAID-Z reconstruction has to traverse the filesystem metadata to determine the actual RAID-Z geometry. This would be impossible if the filesystem and the RAID array were separate products, whereas it becomes feasible when there is an integrated view of the logical and physical structure of the data. Going through the metadata means that ZFS can validate every block against its 256-bit checksum as it goes, whereas traditional RAID products usually cannot do this.

In addition to handling whole-disk failures, RAID-Z can also detect and correct silent data corruption, offering "self-healing data": when reading a RAID-Z block, ZFS compares it against its checksum, and if the data disks did not return the right answer, ZFS reads the parity and then figures out which disk returned bad data. Then, it repairs the damaged data and returns good data to the requestor.

RAID-Z does not require any special hardware: it does not need NVRAM for reliability, and it does not need write buffering for good performance. With RAID-Z, ZFS provides fast, reliable storage using cheap, commodity disks.

There are three different RAID-Z modes: RAID-Z1 (similar to RAID 5, allows one disk to fail), RAID-Z2 (similar to RAID 6, allows two disks to fail), and RAID-Z3 (allows three disks to fail). The need for RAID-Z3 arose recently because RAID configurations with future disks (say, 6–10 TB) may take a long time to repair, the worst case being weeks. During those weeks, the rest of the disks in the RAID are stressed more because of the additional intensive repair process and might subsequently fail, too. By using RAID-Z3, the risk involved with disk replacement is reduced.

Mirroring, the other ZFS RAID option, is essentially the same as RAID 1, allowing any number of disks to be mirrored.

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skipskip

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發表於 2015-4-14 13:34 | 只看該作者

樓主, 如果只係做蚊型公司File Server, 倒不如買部NAS.

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SIFAI

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發表於 2015-4-14 14:21 | 只看該作者

回覆 SIFAI

你有話過唔淘，但你無話過唔用大陸牌子，AND THEN差唔多9成RAID卡都係MIC(MAKE IN CHIN ...
inone2 發表於 2015-4-12 19:30

師兄
我想問下點知佢係跟唔跟線的?
幾多Adaptec 姐係可以連幾多隻HDD?
咁我E+線係咪應買SAS 轉SATA 咁?
因為我唔知四張裏面邊好,但四張都係可以接受的價錢內呢
唔知大大可以講下有咩分別?
MIC 都唔係問題,都無法架啦平野
但斷電保護係咪高階野來? 會唔會貴同唔知邊到睇到佢有呢個功能?
真係好多謝師兄你!! 給我咁多型號
其實我最想要的係型號再加分析!!!

所以謝謝你!!