Neil Brown wrote: > On Tuesday May 2, a1426z@xxxxxxxxx wrote: > > NeilBrown wrote: > > > The "industry standard" DDF format allows for a stripe/offset layout > > > where data is duplicated on different stripes. e.g. > > > > > > A B C D > > > D A B C > > > E F G H > > > H E F G > > > > > > (columns are drives, rows are stripes, LETTERS are chunks of data). > > > > Presumably, this is the case for --layout=f2 ? > > Almost. mdadm doesn't support this layout yet. > 'f2' is a similar layout, but the offset stripes are a lot further > down the drives. > It will possibly be called 'o2' or 'offset2'. > > > If so, would --layout=f4 result in a 4-mirror/striped array? > > o4 on a 4 drive array would be > > A B C D > D A B C > C D A B > B C D A > E F G H > .... Yes, so would this give us 4 physically duplicate mirrors? If not, would it be possible to add a far-offset mode to yield such a layout? > > Also, would it be possible to have a staged write-back mechanism across > > multiple stripes? > > What exactly would that mean? Write the first stripe, then write subsequent duplicate stripes based on idle with a max delay for each delayed stripe. > And what would be the advantage? Faster burst writes, probably. Thanks! -- Al - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
