Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Let me follow up on my own post by asking another question, maybe more for the developers list, why is the max_sectors set to the PAGE_SIZE and not the capabilities of the backing device? Will the driver not handle the kind of throughput that a hardware based RAID card can generate? By setting the max_sectors to 8 from the hardware's 128 severely limits throughput (to 1/3 normal). -Ross > -----Original Message----- > From: drbd-user-bounces at lists.linbit.com > [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Ross > S. W. Walker > Sent: Tuesday, January 02, 2007 4:05 PM > To: drbd-user at lists.linbit.com > Subject: [DRBD-user] Large block IO bottleneck > > > Hi there I am using DRBD 0.7.21 with iSCSI Enterprise Target 0.4.14 on > CentOS 4.4. > > When I run iSCSI direct to the LVM lv on top of hardware RAID > I can get > 225 MB/s over two sessions in MPIO with 256K block size, but > when I put > DRBD in-between iSCSI and LVM the throughput tops out at 80 MB/s and I > can't seem to go over that. > > DRBD seems to report it's max number of sectors as 8 (4K), does that > mean each io operation is limited to 4K? My hardware raid reports it's > max sectors as 128, could this explain the reduction to 1/3 > throughput? > > > > Ross S. W. Walker > Information Systems Manager > Medallion Financial, Corp. > 437 Madison Avenue > 38th Floor > New York, NY 10022 > Tel: (212) 328-2165 > Fax: (212) 328-2125 > WWW: http://www.medallion.com <http://www.medallion.com> > > > > ______________________________________________________________________ > This e-mail, and any attachments thereto, is intended only for use by > the addressee(s) named herein and may contain legally privileged > and/or confidential information. If you are not the intended recipient > of this e-mail, you are hereby notified that any dissemination, > distribution or copying of this e-mail, and any attachments thereto, > is strictly prohibited. If you have received this e-mail in error, > please immediately notify the sender and permanently delete the > original and any copy or printout thereof. > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.