mkfs.xfs parameters for raid array

hvidgaard · 03-06-2006, 07:19 AM

Hi

I am a little in doubt what parameters to use when making my xfs filesystem on a raid5 array with 128kb chunksize. I think I should specify sunit/su and swidth/sw option, but I'm not sure to what.

This is from the man page: http://www.die.net/doc/linux/man/man8/mkfs.xfs.8.html

Quote:

The sunit suboption is used to specify the stripe unit for a RAID device or a logical volume. The suboption value has to be specified in 512-byte block units. Use the su suboption to specify the stripe unit size in bytes. This suboption ensures that data allocations will be stripe unit aligned when the current end of file is being extended and the file size is larger than 512KB. Also inode allocations and the internal log will be stripe unit aligned.
The su suboption is an alternative to using sunit. The su suboption is used to specify the stripe unit for a RAID device or a striped logical volume. The suboption value has to be specified in bytes, (usually using the m or g suffixes). This value must be a multiple of the filesystem block size.
The swidth suboption is used to specify the stripe width for a RAID device or a striped logical volume. The suboption value has to be specified in 512-byte block units. Use the sw suboption to specify the stripe width size in bytes. This suboption is required if -d sunit has been specified and it has to be a multiple of the -d sunit suboption. The stripe width will be the preferred iosize returned in the stat(2) system call.
The sw suboption is an alternative to using swidth. The sw suboption is used to specify the stripe width for a RAID device or striped logical volume. The suboption value is expressed as a multiplier of the stripe unit, usually the same as the number of stripe members in the logical volume configuration, or data disks in a RAID device.
When a filesystem is created on a logical volume device, mkfs.xfs will automatically query the logical volume for appropriate sunit and swidth values.

sP1v · 02-12-2007, 08:11 PM

Quote:

Originally Posted by hvidgaard

Hi

I am a little in doubt what parameters to use when making my xfs filesystem on a raid5 array with 128kb chunksize. I think I should specify sunit/su and swidth/sw option, but I'm not sure to what.

This is from the man page: http://www.die.net/doc/linux/man/man8/mkfs.xfs.8.html

Did you ever find any guides or howtos on setting up an XPS file system? I am attempting todo the same using Software Raid 5 and LVM on a FC6 system, but I am having trouble finding a good installation guide. Any pointers will be greatly appreciated.

-sP1v

hvidgaard · 02-18-2007, 03:51 PM

no not really...

I used (and are still using) the default values. They work okay for me so far (4x250Gb, 100mbit network), but one day when I upgrade to 1Gbit, perhaps some testing should be done to find the best values (could turn out to be the defaults).

My biggest consern are not throughput, but the ability to, lets say, having 2 htpc's streaming at 6-7mbit each, 1 user reading/writing a large file, and the OS doing some random reads and writes (web/mail/shell/VMware server) without the system feeling slow.

If you find any information regarding optimization, I would like to know