[DRBD-user] Metadata on software RAID1 load slowlyness problem

Lars Ellenberg Lars.Ellenberg at linbit.com
Tue Dec 12 11:13:14 CET 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


/ 2006-12-11 22:50:25 -0800
\ joe_p:
> 
> It appears that I also have this same problem with a gentoo 2.6.17.14 kernel
> and drbd 0.7.22
> 
> Today we move the drbd meta to a single drive and drbdsetup ran in a couple
> seconds compared to the 4-5 minutes it was taking.  I applied the patch
> below tried the drbd meta data on the md raid again and did not see any
> difference in behavior.   Once again it took 4-5 minutes for drbdsetup to
> complete.  Is there something else that is needed to be done?

the same thing in the READ path, obviously.
slightly changed patch below.
I still think that reassigning the bi_rw explicitly,
thus stripping off whatever else is in there is a bug.

--- /mnt/kernel-src/linux-2.6.19/drivers/md/raid1.c.orig	2006-12-11 10:06:17.661776243 +0100
+++ /mnt/kernel-src/linux-2.6.19/drivers/md/raid1.c	2006-12-12 11:09:55.975762364 +0100
@@ -776,6 +776,7 @@
 	struct page **behind_pages = NULL;
 	const int rw = bio_data_dir(bio);
 	int do_barriers;
+	int do_sync = bio_sync(bio);
 
 	/*
 	 * Register the new request and wait if the reconstruction
@@ -835,7 +836,7 @@
 		read_bio->bi_sector = r1_bio->sector + mirror->rdev->data_offset;
 		read_bio->bi_bdev = mirror->rdev->bdev;
 		read_bio->bi_end_io = raid1_end_read_request;
-		read_bio->bi_rw = READ;
+		read_bio->bi_rw = READ | do_sync;
 		read_bio->bi_private = r1_bio;
 
 		generic_make_request(read_bio);
@@ -906,7 +907,7 @@
 		mbio->bi_sector	= r1_bio->sector + conf->mirrors[i].rdev->data_offset;
 		mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
 		mbio->bi_end_io	= raid1_end_write_request;
-		mbio->bi_rw = WRITE | do_barriers;
+		mbio->bi_rw = WRITE | do_barriers | do_sync;
 		mbio->bi_private = r1_bio;
 
 		if (behind_pages) {

-- 
: Lars Ellenberg                            Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH      Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe    http://www.linbit.com :
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