Yes, I just issue 'reboot' on Server A. But I am curious about why 'some' request will lost to other server. Is It should be only one request lost(the last IO committed ) according to full sync strategy. 2015-03-22 13:38 GMT+08:00 NeilBrown <neilb@xxxxxxx>: > On Sun, 22 Mar 2015 13:00:54 +0800 lingli tang <tanglingli001@xxxxxxxxx> > wrote: > >> Thanks for reply. >> >> I have create a raid1 with two fusion io PCIe flash disk: >> mdadm --create /dev/md/master --name=master --level=1 --raid-devices=2 >> /dev/fioa2 /dev/mapper/mpathc >> /dev/fioa2 is local disk on server A and /dev/mapper/mpathc is a iscsi >> load disk export from server B. >> >> After that we mkfs.ext4 on /dev/md/master and mount with 'sync' option on /data1 >> and we will run mysql binlog on it. >> In order to avoid data loss of mysql binlog we have set >> sync_binlog=1. so every sql commit will call fsync() to flush to disk. >> >> according to your description. if we reboot the server A, the two disk >> data on different server will be the same. >> but after the server A restarted, we assemble the two disk on two >> server, data is different on the two server, disk on server B lost >> more than one sql commit. > > What exactly do you mean by "reboot"?? > Is this a clean shutdown or do you remove the power or something like that. > > If you remove the power, then it is very possible that some requests will > have been submitted to one device but not the other. > If you have a clean shutdown, then the two devices should be identical. > > NeilBrown > > >> >> I have checked it with strace 'mysqld' on Server A. >> I found a sql commit and fsync() on binlog file handle on server A but >> this sql can not find in assembled disk on server B. >> >> I also test it with two SAS disk, Server B still has more than one sql >> commit lost. >> >> >> 2015-03-22 11:20 GMT+08:00 NeilBrown <neilb@xxxxxxx>: >> > On Sat, 21 Mar 2015 19:01:54 +0800 lingli tang <tanglingli001@xxxxxxxxx> >> > wrote: >> > >> >> I am a newbie of mdadm. I have a question but find no answer in >> >> document or google for last 10 days. >> >> >> >> The question is : RAID1 made by mdadm is full sync? for example, I >> >> have two disk(sdb and sdc) to make RAID1 disk (/dev/md127), if I >> >> commit an IO to the RAID1 disk (md127), it will return back to me when >> >> all the two disk commit successfully or it will return back >> >> to me once just one of the disk successfully commit. >> > >> > The write request will not return until it has been submitted to all, and >> > returned by, all working devices. >> > >> >> >> >> I have test with xfs and ext4 with sync option, and it seems that two >> >> disk have lots of commit difference after reboot the server. is that >> >> means mdadm return success when one of the disk is commit >> >> successfully? >> > >> > That certainly shouldn't happen. I would need more details of the experiment >> > that you performed. >> > >> > NeilBrown >> > >> > >> >> -- >> >> 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 >> > > -- 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
