[raid 卡] RAID 5 極慢,唔知樽頸o係邊度

本帖最後由 chrisyw 於 2012-7-28 00:20 編輯

PC: IBM System x3620 M3
HDD: 2TB SATA 7200rpm x 8
RAID Controller: ServeRAID M1015 SAS/SATA Controller (唔支援RAID 6)
RAID: RAID 5 (7 harddisks) + 1 hot spare harddisk

Host OS: VMWare ESXi 5.0
Guest OS: Debian Linux 6.0


Write Test:

# dd if=/dev/zero of=/home/testing.img bs=8k count=128k conv=fdatasync

test 1: 1073741824 bytes (1.1 GB) copied, 94.0746 s, 11.4 MB/s
test 2: 1073741824 bytes (1.1 GB) copied, 47.4879 s, 22.6 MB/s
test 3: 1073741824 bytes (1.1 GB) copied, 48.7925 s, 22.0 MB/s
test 4: 1073741824 bytes (1.1 GB) copied, 115.86 s, 9.3 MB/s

Read Test:
# hdparm -tT /dev/sdb

test 1:
Timing cached reads:   15680 MB in  2.00 seconds = 7847.77 MB/sec
Timing buffered disk reads: 678 MB in  3.00 seconds = 225.85 MB/sec

test 2:
Timing cached reads:   16190 MB in  2.00 seconds = 8103.83 MB/sec
Timing buffered disk reads: 668 MB in  3.00 seconds = 222.61 MB/sec

test 3:
Timing cached reads:   15582 MB in  2.00 seconds = 7799.29 MB/sec
Timing buffered disk reads: 688 MB in  3.01 seconds = 228.71 MB/sec

test 4:
Timing cached reads:   16180 MB in  2.00 seconds = 8098.71 MB/sec
Timing buffered disk reads: 704 MB in  3.01 seconds = 233.86 MB/sec


請問點解Write Test咁慢呢?
係唔係RAID 太大,需要減少harddisk?
4 harddisks 做RAID 5會唔會快D?

M1015只係一張有RAID的HBA

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M1015只係一張有RAID的HBA
cccccctt 發表於 2012-7-28 00:38


有少少中伏既感覺(雖然server唔係我買)
請問點樣改善write performance?減少raid 5 harddisk ?還是索性用software raid算

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回復 3# chrisyw


    no raid 5, change to others

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你的應用有無話要:
1. Read要快過Write;
2. Write要快過Read;
3. Read / Write 要一樣快?

即係你有四粒星: ****, 你選那一種?
***/*
*/***
**/**

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想快就一定raid 0如果怕唔見data就raid0+1-2backup la

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HBA卡, 基本上只預你用RAID-0 / RAID-1 / RAID-10
其他既, 換卡吧
同埋你bs=8k, 會唔會細左D?
試下用大D block size, 應該會快D

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1015 唔預行 Raid 5

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本帖最後由 chrisyw 於 2012-7-30 01:26 編輯
你的應用有無話要:
1. Read要快過Write;
2. Write要快過Read;
3. Read / Write 要一樣快?

即係你有四粒 ...
uxuq 發表於 2012-7-28 14:30


其實write 唔需要好快, 30-50MB/s 已經可以接受
Read 我希望有80-90MB/s, 因為多read operation
而家問題唔止慢,透過windows explorer 上傳檔案(~2GB)100%後,explorer會freeze十幾秒先有反應

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