On Sonntag 19 Juli 2009 Linda Walsh wrote:
> Then, for RAID 1 (mirror) would 'sw'==1? Would setting the su/sw
> value for a RAID 1 actually matter in any way? Ie, technically --
> it would fill in numbers for OS book-keeping, but wouldn't change
> anything in terms of performance or layout, vs. 'physically' -- where
> it could change disk layout or performance?
> At RAID 0, I'd guess sw==2?
Both RAID0 and RAID1 use sw=0.
> In RAID 5, would it be sw == #Disks-1? So even w/6 disks, it
> still only uses 1 disk for parity and sw == 5?
RAID5: sw = #Disks-1 ( so with 8 disks use 7)
RAID6: sw = #Disks-2 ( so with 8 disks use 6)
> I wonder what becomes a max-safe RAID 5 size? (or is the number of
> parity disks a settable option with RAID 5?)
RAID5 always only has 1 parity disk (well, technically it's not a
physical disk, but the parity is distributed over all disks in the
Don't know what you mean by "max-safe" size. The more disks you have,
the bigger the chance that a single disk breaks. Also, I tested with
Areca controllers, using more than 7 disks in a single RAID array
doesn't improve speed anymore. So I use RAID-6 for up to 8 disks, and
make it RAID-60 for up to 16 disks (with Areca controllers).
// Michael Monnerie, Ing.BSc ----- http://it-management.at
// Tel: 0660 / 415 65 31 .network.your.ideas.
// PGP Key: "curl -s http://zmi.at/zmi.asc | gpg --import"
// Fingerprint: AC19 F9D5 36ED CD8A EF38 500E CE14 91F7 1C12 09B4
// Keyserver: wwwkeys.eu.pgp.net Key-ID: 1C1209B4
Description: This is a digitally signed message part.