TRACKER_MAN

best stripe size for RAID5 on ICH10R

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Hello guys,

i am working on one idea to make RAID5 with 4 disks Samsung HD103UJ (1TB) with my mobo ICH10R controller.

i want to ask you what you do you think about best stripe size for RAID5 when using 4 disks samsung?

Thank you for answers!

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RAID5 with 4 disks Samsung HD103UJ (1TB) with my mobo ICH10R controller.

i want to ask you what you do you think about best stripe size for RAID5 when using 4 disks samsung?

I guess your usage is a desktop one where random io and io queue length are not very important.

Please consider

a/ HD103UJ is not a RAID edition drive

  • No CCTL feature means any io error may lead to the drive being seen as "disconnected" by the ICH10R
  • 0.8% read error probability per 1TB read (1 bit per 10exp15 bits read) means you have a 2.4% risk of a 2d drive failing at rebuild time

b/ RAID 5 with 4 drives does not allow a "full stripe size" of a 4KB multiple

4KB stripe (example) on each drive means 12KB full stripe size. A NTFS cluster size of 4, 8, 16, 32 or 64KB, you can not optimize your array for a desktop usage.

Please read my favorite reference here How to achieve superb write speeds with nForce onboard RAID5 @ StorageReview

c/ RAID 10

Safer, faster, easyer to configure. Full point.

Now for the stripe size

1/ RAID 5 with 3 (or 5) large sata drives used for Desktop usage

Use 32KB (or 16KB) stripe for a full stripe size of 64KB

2/ RAID 5 on a hw raid card with a large "write back cache" backed by a battery

Use 64KB stripe size or the io size used by your client apps (NTFS-XP-Win2003 uses 64KB, NTFS-Vista-Win2008 uses 1MB, DBMS uses 4-8-16-32 or 64KB page size)

3/ Other RAID 5 conf

Will suffer severe write performance problem. Full point.

4/ RAID 10

Use 64KB stripe size or the io size used by your client apps (NTFS-XP-Win2003 uses 64KB, NTFS-Vista-Win2008 uses 1MB, DBMS uses 4-8-16-32 or 64KB page size)

Rules of thumb:

  • Align your partition regarding to your array conf (Use Diskpart)
  • Use NTFS cluster size equals to the stripe size (or full stripe size for RAID 5 [1/ above])
  • backup, keep your backup out of obvious risks (childs, fire and thiefs)

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i am working on one idea to make RAID5 with 4 disks Samsung HD103UJ (1TB) with my mobo ICH10R controller.

i want to ask you what you do you think about best stripe size for RAID5 when using 4 disks samsung?

The default stripe size should be fine for this configuration, provided that the write-back cache is enabled. There is some increased risk of data loss with this configuration, so it's not recommended if you have unstable power or an unstable configuration, random boots and crashes / etc., but otherwise it's a decision you can make yourself trading off some risk for greater write performance.

Here's a chart of simple sequential performance measurements with a similar but older Intel RAID configuration:

ir5-3vs4-wb-on-vs-off.png

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a chart of simple sequential performance measurements with a similar but older Intel RAID configuration

RAID 5 random write io are at least 3x slower than RAID 1/10 random write io.

Please read again below and go with RAID 10

b/ RAID 5 with 4 drives does not allow a "full stripe size" of a 4KB multiple

4KB stripe (example) on each drive means 12KB full stripe size. A NTFS cluster size of 4, 8, 16, 32 or 64KB, you can not optimize your array for a desktop usage.

Please read my favorite reference here How to achieve superb write speeds with nForce onboard RAID5 @ StorageReview

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Hello again.Thanks for your answers. The configuration will be used for desktop, not for server use. I have tried sample raid5 with 3 discs and 32k stripe, NTFS 64kb cluster,aligned partition and STR was ~ 160MB/s and writing 100MB/s. I will check other example configs with 64k stripe when i got 4th disk. that's all for the moment :rolleyes: keep waiting for 4th disk...

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I have tried sample raid5 with 3 discs and 32k stripe, NTFS 64kb cluster,aligned partition.

64 KiB clusters can waste a lot of space if you have many small files. Test with the default cluster size as well to see if it makes a big difference.

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Yeah, i have big troubles with my ICH10R - silent corruption :ph34r: So i have decided to make another machine with solaris and zfs for NAS. And now i am happy! :rolleyes:

Edited by TRACKER_MAN

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