[DRBD-user] Performance with DRBD + iSCSI

Ross S. W. Walker rwalker at medallion.com
Wed Feb 21 20:22:22 CET 2007

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

> -----Original Message-----
> From: drbd-user-bounces at lists.linbit.com 
> [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Weilin Gong
> Sent: Wednesday, February 21, 2007 1:11 PM
> Cc: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] Performance with DRBD + iSCSI
> Ross S. W. Walker wrote:
> > You can only write into drbd using what your application 
> can handle and
> > for VFS file operations that is 4k io! 
> On Solaris ufs, the "maxcontig" parameter can be tuned to specify the 
> the number of contiguous
> blocks written to the disk. Haven't found the equivalence on 
> Linux yet.

Well, if you write your own app you can bypass VFS page-memory io
restriction by using the generic block layer.

I'm not sure if you quite understand the maxcontig parameter either:

maxcontig=n The maximum number of logical
blocks, belonging to one file, that
are allocated contiguously. The
default is calculated as follows...

This parameter is for tuning disk space allocation in order to reduce
fragmentation, it doesn't affect the io block size.


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