Hi,
[first of all i'm not really sure if i'm right here. If this is the
wrong place then please just
tell me what to rtfm or where to post]
i'm currently trying to create a raid 5 out of three 1 TB hdd. For now
there is one hdd missing so i get 3 TB of usable space.
One hdd is connected to
00:07.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller (rev f3)
the other two to
04:00.0 RAID bus controller: Silicon Image, Inc. SiI 3132 Serial ATA
Raid II Controller (rev 01)
The CPU is a AMD X2 4200+ and the system has 2 GB RAM.
The performance of the array is underwhelming.
time dd if=/dev/zero of=big_file bs=4096 count=2560000
10485760000 bytes (10 GB) copied, 187.691 s, 55.9 MB/s
dd if=/dev/zero of=big_file bs=4096 count=2560000 0.70s user 26.05s
system 14% cpu 3:08.12 total
time dd if=big_file of=/dev/null bs=4096 count=2560000
10485760000 bytes (10 GB) copied, 297.345 s, 35.3 MB/s
dd if=big_file of=/dev/null bs=4096 count=2560000 0.50s user 10.60s
system 3% cpu 4:57.35 total
So i get a write performance of 55 MB/s and a read speed of 35 MB/s. The hdd
Model=SAMSUNG HD103UJ , FwRev=1AA01113,
SerialNo=S13PJDWS250990
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
BuffType=DualPortCache, BuffSize=32767kB, MaxMultSect=16, MultSect=?16?
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=1953525168
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 udma6
AdvancedPM=yes: unknown setting WriteCache=enabled
Drive conforms to: unknown: ATA/ATAPI-3,4,5,6,7
are all the same and get ~70 MB/s when used alone.
The details for the raid device:
/dev/md6:
Version : 00.90
Creation Time : Sun Apr 19 22:30:23 2009
Raid Level : raid5
Array Size : 2930279424 (2794.53 GiB 3000.61 GB)
Used Dev Size : 976759808 (931.51 GiB 1000.20 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 6
Persistence : Superblock is persistent
Update Time : Mon Apr 20 14:45:32 2009
State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 256K
UUID : 584a0f66:3c075c23:9cae9464:25382498 (local to host
johannes-desktop)
Events : 0.21396
Number Major Minor RaidDevice State
0 8 97 0 active sync /dev/sdg1
1 8 145 1 active sync /dev/sdj1
2 8 161 2 active sync /dev/sdk1
3 0 0 3 removed
On top of the raid device there is a crypto layer
cryptsetup --verify-passphrase -c aes-cbc-essiv:sha256 -y -s 256
luksFormat /dev/md6
and then ext4
mkfs.ext4 -v -b 4096 -E lazy_itable_init,stride=64,stripe-width=256 -O
large_file,dir_index,extent,sparse_super,uninit_bg -m0
/dev/mapper/data
I use kernel 2.6.29.1
Stride and stripe-width will be correct when i add another two hdd of
which one will carry data. Can someone please give me a hint why i
could get such bad performance especially while reading? I don't think
its the crypto layer since kcryptd doesn't go over 50% cpu and having
two cores should prevent other processes from starving. The stride and
stripe-width aren't correct right now but can it degrade performance
like that? I would expect at least 100+ MB/s on reading and writing.
Thanks
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