> -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid- > owner@xxxxxxxxxxxxxxx] On Behalf Of aristizb@xxxxxxxxxxx > Sent: Thursday, July 31, 2008 10:04 AM > To: linux-raid@xxxxxxxxxxxxxxx > Subject: RAID1 write order fidelity > > Hi, > > I am currently working with a software Linux RAID1, with external > bitmap and no write-behind option. Does the RAID controller keep the > write order fidelity?. > > If an application writes some blocks on the RAID device in a > particular order, can I ensure that these blocks will be written to > the devices conforming the RAID on the same order, or at least on the > main disk? (disk 0 on the RAID). > > > The version of mdadm I am suing is 2.6.2. > > > Thank you. > > > Juan Aristizabal. The answer is no. Well-designed RAID controllers will prioritize queued I/Os for best performance. And, for that matter, device drivers, BIOS, even some file systems will move around I/Os for purposes of optimization and response time, so this isn't necessarily a RAID-controller specific response. They may even eliminate writes completely based on cache settings, what is in the queue, the block range, and the number of blocks for the I/O requests. David @ santools dot com -- 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
