16Kb Cluster size - How?

[Wayne Youngman]

Hi all,

I will be setting my RAID-0 array up soon and I was wondering how you
*custom* specify the cluster size (not stripe size) of my array. I never
saw an option before when formatting that lets you adjust the Cluster size?
Mine always seem to be 4Kb. I heard that 16Kb cluster size with a 16Kb
stripe size can *edge* up disk performance slightly. . .

many thanks,

 

[Andrew Rossmann]

[This followup was posted to comp.sys.ibm.pc.hardware.storage and a copy
was sent to the cited author.]

I will be setting my RAID-0 array up soon and I was wondering how you
*custom* specify the cluster size (not stripe size) of my array. I never
saw an option before when formatting that lets you adjust the Cluster size?
Mine always seem to be 4Kb. I heard that 16Kb cluster size with a 16Kb
stripe size can *edge* up disk performance slightly. . .

Cluster size is set by the FORMAT command. If you format inside Windows,
there is usually a drop-down box for 'allocation size' or similar. From a
command prompt, you can try:
FORMAT x: /A:16K

Be aware that NTFS with cluster sizes over 4K may lose features like
compression and defragmentation. That's why NTFS usually defaults to 4K.

 

[S.Heenan]

Hi all,

I will be setting my RAID-0 array up soon and I was wondering how you
*custom* specify the cluster size (not stripe size) of my array. I never
saw an option before when formatting that lets you adjust the Cluster size?
Mine always seem to be 4Kb. I heard that 16Kb cluster size with a 16Kb
stripe size can *edge* up disk performance slightly. . .

The default size for NTFS clusters is 4KB. Leave it as is.
As for stripe size, default is probably 64KB. Set it higher if you plan to
be working with large video files.

 

[Shailesh Humbad]

I benched 4KB cluster/4KB stripe versus 512B cluster/16KB stripe, and
found the latter, default setting to be slightly (~5%) faster for
large file operations. In Windows XP, just right-click on the drive,
select format, and choose the cluster size. My XP Pro doesn't show a
16KB cluster size option; the highest is 4096 bytes. In general,
cluster size of a partition is set from the OS's format function
whereas stripe size is set from the BIOS of the RAID controller.

 

[Oldguy]

MSKB search for "cluster size windows xp" produced:
http://www.microsoft.com/resources/...Windows/XP/all/reskit/en-us/prkc_fil_lxty.asp
Adjoining articles on same page give info on Fat limitations and the XP file
system itself among other topics.