Solaris

Hello every body,
Maybe someone could help me.
I have a SUN Server with 6 disks, each of 150 Gb.
I have mounted the first two disk in mirror (RAID1) for the system files.
I have mounted 3 disks in RAID5 for users file systems.
I kept the last one as spare and I have mounted it standalone (RAID0).
I made a test with a 1Gb file :
the copy from RAID1 to RAID0 is 25 seconds.
the copy from RAID1 to RAID5 is 10 minutes !!
I think that it may be something wrong in the configuration.
Thanks for your help.
Alain

Are you using SVM? Post the output from metastat.

I guess you are using RAID 5 from SVM. It is not a good thing at all.
1 Write to RAID 5 will give you:
1) 1 Read from the RAID 5 to calculate the parity for the new data
2) 1 write to Update the new data
3) 1 write to Update the new parity

The 1 Write will cause 1 Read + 2 Write in RAID 5 environment.

Golden Rule: Fast, Safe, Cheap, choose 2.
Raid 5: Safe and Cheap
RAID 1: Safe and Cheap
Raid 0: Fast and Cheap
RAID 10: Fast and Safe

Yes I use SVM.
Here is the result of metatstat :
d30: Mirror
Submirror 0: d31
State: Okay
Submirror 1: d32
State: Okay
Pass: 1
Read option: roundrobin (default)
Write option: parallel (default)
Size: 31464192 blocks (15 GB)

d31: Submirror of d30
State: Okay
Size: 31464192 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t0d0s3 0 No Okay Yes


d32: Submirror of d30
State: Okay
Size: 31464192 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t1d0s3 0 No Okay Yes


d20: Mirror
Submirror 0: d21
State: Okay
Submirror 1: d22
State: Okay
Pass: 1
Read option: roundrobin (default)
Write option: parallel (default)
Size: 62928384 blocks (30 GB)

d21: Submirror of d20
State: Okay
Size: 62928384 blocks (30 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t0d0s1 0 No Okay Yes


d22: Submirror of d20
State: Okay
Size: 62928384 blocks (30 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t1d0s1 0 No Okay Yes


d10: Mirror
Submirror 0: d11
State: Okay
Submirror 1: d12
State: Okay
Pass: 1
Read option: roundrobin (default)
Write option: parallel (default)
Size: 31464192 blocks (15 GB)

d11: Submirror of d10
State: Okay
Size: 31464192 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t0d0s0 0 No Okay Yes


d12: Submirror of d10
State: Okay
Size: 31464192 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t1d0s0 0 No Okay Yes


d40: Mirror
Submirror 0: d42
State: Okay
Submirror 1: d41
State: Okay
Pass: 1
Read option: roundrobin (default)
Write option: parallel (default)
Size: 32909184 blocks (15 GB)

d42: Submirror of d40
State: Okay
Size: 32909184 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t1d0s4 0 No Okay Yes


d41: Submirror of d40
State: Okay
Size: 32909184 blocks (15 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c1t0d0s4 0 No Okay Yes


d110: RAID
State: Okay
Interlace: 32 blocks
Size: 142443648 blocks (67 GB)
Original device:
Size: 142463296 blocks (67 GB)
Device Start Block Dbase State Reloc Hot Spare
c1t2d0s7 330 No Okay Yes
c1t3d0s7 330 No Okay Yes
c1t4d0s7 330 No Okay Yes

d100: RAID
State: Okay
Interlace: 32 blocks
Size: 141426048 blocks (67 GB)
Original device:
Size: 141445696 blocks (67 GB)
Device Start Block Dbase State Reloc Hot Spare
c1t2d0s6 330 No Okay Yes
c1t3d0s6 330 No Okay Yes
c1t4d0s6 330 No Okay Yes

d50: Concat/Stripe
Size: 286169472 blocks (136 GB)
Stripe 0:
Device Start Block Dbase Reloc
c1t5d0s6 0 No Yes

Device Relocation Information:
Device Reloc Device ID
c1t5d0 Yes id1,ssd@w500000e0113c0e20
c1t0d0 Yes id1,ssd@w500000e0113b96e0
c1t1d0 Yes id1,ssd@w500000e0113b9040
c1t2d0 Yes id1,ssd@w500000e0113c0e30
c1t3d0 Yes id1,ssd@w500000e0113c12f0
c1t4d0 Yes id1,ssd@w500000e0113b97f0

You might want to look into not using RAID-5 for your user files. If you use all four of your remaining disks you might be able to do a RAID 1+0. You will not lose any disk space as you do with RAID 5 also. Here is a link that might help you out.

http://www.ncell.com/~russj/DiskSuite-RAID1+0.html

A basic rule of thumb is:

Never implement raid 5 in software. If your hardware doesn't support it it's not worth using because of the cost of parity calculation as ppointed out in an earlier post. I is much better to go with a striped & mirorred strategy for performance. The cost in hardware is much much less for RAID5 and so it becomes viable.

Just to add : raid5 in software is NOT CPU costly (you can do it easily under WServer2K or 2K3 with lot's of very fast drives without significant CPU penalty) anymore (even since many years).
Parity processing of 100+MB/s is pinuts for modern CPUs.

So you have big problem somewhere... Note that RAID5 is not really aimed at big I/O size but you should get far better performance for 1MB file.

BUT you should use hardware raid5 because of many other reasons like hotswap, hotspare, performances, security in case of brutal power off while writing ...