Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Dan, Without getting too deep into your stack....can you test this with a local (LAN) based DRBD resource vs. a remote one? Even with 28ms of latency, there could be something in your network causing some bottlenecks stopping DRBD from doing it's job properly. I've seen high-bandwidth low-latency links act similarly due to an unseen network policy (not DRBD's fault, simply put...you can't put a man on the moon without the proper fuel...no fuel no fly). If I understand correctly what your layout is...it would be wise to segment your servers from your network to troubleshoot. If DRBD works great in a LAN environment (cross connect) cable....then it is not your server, it is your network. Vice versa....if it works horribly with a cross connect as well...then you have something going on inside your server...software or hardware. Hope this helps. Best, -Kavan Dan Lavu wrote: > Digi, > > I posted most everything on the initial email, but to recap, I'm pretty > sure it's a disk issue. > > When copying a large file to the raid, using SFTP I see IO read and > write times of 30-35MB/s and I see transfer rates of 20MB/s. Keep in > mind I'm syncing between two datacenters, Texas to Illinois. > > When it's syncing, iostat shows read write times of 2MB/s. I even > created a ramdisk for an external metadisk and I saw no improvement. > > If my raid can easily write at 30MB/s why is the DRBD sync capped at > 2MB/s? This is a RAID 5, with two logical volumes. > > Thanks, > > Dan Lavu > > > > -----Original Message----- > From: Digimer [mailto:linux at alteeve.com] > Sent: Monday, February 15, 2010 5:30 PM > To: Dan Lavu > Cc: drbd-user at lists.linbit.com > Subject: Re: [DRBD-user] DRBD - Slow Performance > > Dan Lavu wrote: >> Digi, >> >> Thanks for advance again, but I've already tried this. I'm still > pegged >> at 2MB/s. I've exhausted IRC any google searches involving DRBD slow >> sync. I'm really contemplating rebuilding the machine with a RAID 10 > to >> enhance performance but I still do not know if this is going to > resolve >> the issue, any thoughts about this? Thanks in advance. >> >> Best Regards, >> >> Dan Lavu > > How is performance on the local disk? Have you checked using something > like: fdisk -tT /dev/sda? Also, what performance do you get if you write > > a large file to the array? > > What I am wondering is; Is the performance limitation a DRBD issue, a > disk issue or a sync'er issue. What kind of performance do you get > sending a file over the DRBD's network interfaces directly (not writing > to the DRBD disk)? > > Digi > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > -- : Kavan Smith : LINBIT | Your Way to High Availability : Telephone: 503-573-1262 ext. 201 : Sales: 1-877-4-LINBIT / 1-877-454-6248 : : 7959 SW Cirrus Dr. : Beaverton, OR 97008 : : http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. This e-mail is solely for use by the intended recipient(s). Information contained in this e-mail and its attachments may be confidential, privileged or copyrighted. If you are not the intended recipient you are hereby formally notified that any use, copying, disclosure or distribution of the contents of this e-mail, in whole or in part, is prohibited. Also please notify immediately the sender by return e-mail and delete this e-mail from your system. Thank you for your co-operation.