Re: [HELP] RAID chunk-size - alternatives
hi ya russell
On Tue, 2 Apr 2002, Russell Coker wrote:
> On Tue, 2 Apr 2002 13:48, Alvin Oga wrote:
> > chunk size does NOT matter for raid5...
> Chunk size does not matter for RAID-1, but does matter for other RAID levels.
humm ..thought was the otehr way ... time for me to go look at some
raid source code i suppose .. when time permits
> > if your disk was partitioned as... 2K bytes/inode...
> You probably mean 2K blocks. The number of bytes per inode just determines
> the size of the inode tables.
yuppers ... and a block is 512bytes ( aka a sector )
and 63 sectors per track (aka cylinder)
and number of cylinders give you the size-of-your-disk
> > it also makes a difference if you used a inode size of 1K or 2K or 4k
> > during disk partitioning
> > - lots of little files or few huge/gigantic files ??
> If you have lots of little files then if you want good write performance then
> you want RAID-1 or RAID-10. RAID-5 is the cheap alternative.
hummm ..... thinking outloud....
"cheap" is relative???
- $$$ for disks vs "(usable) disk space lost to raid"
typically a minimum of 2 disks used for raid0 or raid1...
raid1(mirroring) protects against one disk failure
( one disk's capacity is used as a redundant copy and not for user)
( 50% lost of space )
raid0(stripping) does not help for disk failures
typically 5 disks for raid5 ...
( 3 disks mininum -- 1/3 of your disks lost to parity
( 4 disks .......... 1/4 of your disks lost to parity
( 5 disks .......... 1/5 of your disks lost to parity
typically raid01 - needs 4 disks ...
first data is stripped across 2 disks than its mirrored to 2 more disks
- due to mirroring... 2 disks is lost for "mirror"
and after its all said and done... pull out a disk (simulated disk crash)
and see if you're data is still intact
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