RAID Partition howto

[CA1311635]

Hi everyone,
What shouldbe breakup of 14*146GB SCSI Drives.Fom maximum I/O performance and efficient revovery as file server ( files size 10K -500MB) what is optimal for about 2 TB storage
1 . Single Logical Drive , Single WindiwsVol and single partition.
2 . Single logical Drive, Multiple Volumes and at least three partitions.
3 . Multiple Logical drives m Multiple vol and partitions
Any ideas .Any good pointers /links .
Thanks

[Steven Clementi]

Azhar:

For max i/o performance, you usually want to include as many drives into one array as possible. In your case, you can have 1 array of 14 drive. Are you going to use RAID5? RAID ADG? What about a hot spare?

So, Array A: (14*146 = 2TB at RAID0, 1TB at RAID1+0, @1.85TB at RAID5 and @1.7TB at RAID ADG, all with no Hot Spare)

If this is going to be strictly a file server, then you might get away with one drive. I would probably consider making multiple Logical drives. 1 with a small stripe size and 1 with a larger stripe size to fine tune the performance of your reads nad writes for different size files.

I would not consider creating multiple partitions on 1 logical drive as that can limit your future expandability.


Steven

[CA1311635]

RAID ADG is good as it gives two drive fault tolerance but documentation says its slower than RAID 5 so i think i should go by RAID-5. No hot spare rightnow . If I make multiple logical dirve again I loose space. Is the defualt stripe size of RAID-5 is Ok for File serving?
Does two logical drive provide any advantage in recovery over single logical drive? Are there any performance/recovery gains if i make 3 partitions?
TIA

[Steven Clementi · Accepted solution]

If you create multiple RAID5 logical drives, you do not lose any extra space.
As you create your logical drives, ACu will only show you the "available space as the ARRAY is taking care of the overhead.

In otherwords... if you have 300GB to make a Logical drive out of... and you only specify 150GB for the first drive, you will have 150 left to make the second logical drive. Or maybe 149.99GB.


Is the defualt stripe size of RAID-5 is Ok for File serving? I have not done much with testing different stripe sizes, only reading of help material. Here is part of that text...

Testing with stripe size has produced the following generalities for simple environments:


In a mixed read/write environment: The default stripe size is recommended.
In an environment with more reads than writes: Larger stripe sizes are typically better.
In an environment with more writes than reads: For RAID0, or RAID 1+0, larger stripe sizes are typically better. For RAID4 or RAID5, smaller stripe sizes are typically better.



Does two logical drive provide any advantage in recovery over single logical drive? In some ways, it can make recovery less painful. If you only lost data on onw of the logical drives for some reason or if you need to restore 2 logical drives... one would finish sooner and be available quicker.

Are there any performance/recovery gains if i make 3 partitions? Gains? Probably not too many. Admin wise, it might be more involved having to recreate partitions during crunch time. Performance should be able the same since you still hitting the same number of drives. maybe a bit less because of minimal OS overhead.


Steven

[Uwe Zessin]

Using multiple volumes is good in some areas:
- different failure domains
- less data to restore if one volume fails
- can better run parallel backups

and bad in some other areas:
- each volumne has its own free space management
- this can lead to moving directory trees around if one volumne gets full

[Jarred Martus]

Good Info in this forum. Steve what links were you looking at reading the info about raid speeds, etc. was it on an hp site