Hi Paul, Thanks for your reply. Where can we get documentation (design/implementation) about RAID6 and bitmap for linux kernel 2.6. Thanks and Regards Yogesh -----Original Message----- From: Paul Clements [mailto:paul.clements@xxxxxxxxxxxx] Sent: Wednesday, March 22, 2006 11:37 PM To: Yogesh Pahilwan Cc: 'Neil Brown'; linux-raid@xxxxxxxxxxxxxxx Subject: Re: Linux MD RAID5/6 bitmap patches Yogesh Pahilwan wrote: > Thanks for your reply. As far as what I understood that when we apply the > bitmap patch, for every write it will do 2 sync writes that is setting the > dirty bit, writing intent log and one async write for clearing the dirty > bit. Is it correct? The bits are in the intent log, so the "setting dirty bit" and "writing intent log" are the same thing. Just one write. > If that is the case are there any patches available which can do collection > of sync write in a queue and write a collection in single write request. > For Eg: > For 10 writes , we will have 10 + 1 sync writes + 10 async write. The bitmap code already does this by default. The bitmap writes are queued up so that all writes to a given page (within a short time period) are reduced to a single write. The performance is actually quite good. There's very little performance difference between having a bitmap versus not having one. > I mean to say , 10 sync writes for setting the dirty bits + 1 sync write for > write intent log for all queued request in one write operation + 10 async > write for clearing the dirty bit. The async writes for clearing the bitmap are also combined. -- Paul - 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
