creating new array

Artur Makówka
2008-03-04T16:31:13Z

i want to create new array, because my last one (raid 0) is gone... now
it is going to be raid 5.

this will be on xfs fs of course. now the problem is i don't really know
what chunk size i should use, to get the best performance, but i can
still mount old array read-only and check what is average file size
there - just don't know how. (doing ls -lR * , adding sizes and dividing
by number is probably going to take days to complete)

there was some xfs command that showed it, but i really have no idea
what it was, xfs_info doesnt give me much information

the currect situation is like this:

meta-data=/dev/md0 isize=256 agcount=32, agsize=5723342
blks
= sectsz=512 attr=0
data = bsize=4096 blocks=183146912, imaxpct=25
= sunit=2 swidth=6 blks
naming =version 2 bsize=4096
log =internal bsize=4096 blocks=32768, version=2
= sectsz=512 sunit=0 blks, lazy-count=0
realtime =none extsz=24576 blocks=0, rtextents=0

some of the files are not on it anymore, as i said, it is damaged RAID 0

the system is going to have millions of small files, (up to 3MB), or
even hundreds of millions (very popular free hosting)

could you advice me any xfs and mdadm options? i plan to use lazyblocks
option with latest 2.6.24 kernel. any other ideas?

this is going to be RAID 5, the stability is NOT very important, i will
have full backups, the most important thing is performance. i can get
hundreds of hits per second at peak times, i was planning to build it
from 5 * 500GB disks and it will be just partition for users file,
system is on another disk. (probably on lvm to give me option to resize
it in future)

fs performance is critical, as i have many thousands of accounts, mostly
with just small websites, so it's impossible to put it all in RAM.

if you have any xfs/mdadm creating advice (or mounting options), please
share with me. i installed xfsprogs 2.9.7, and i will compile 2.6.24
kernel for creation time ( i can even risk using 2.6.25-rcX if there is
some important thing changed that i need durning array/filesystem
creation, just not -mm as XFS version from -mm once corrupted some of my
users files )