Date: Fri, 09 Jan 2009 08:38:02 +0200 From: Danny Braniss <danny@cs.huji.ac.il> To: Sossi Andrej <asossi@dotcom.ts.it> Cc: freebsd-scsi@freebsd.org Subject: Re: ISCSI slow to read from DELL MD3000i Message-ID: <E1LLB0M-000OZp-Ms@kabab.cs.huji.ac.il> In-Reply-To: Your message of Thu, 08 Jan 2009 16:36:13 %2B0100 .
next in thread | raw e-mail | index | archive | help
> Danny Braniss wrote: > >> Danny Braniss wrote: > >> > >>> wups, didn't read all your mail, sorry, > >>> try increasing tht tag opening, in the config file add > >>> tag = 64 > >>> for example, or via camcontrol > >>> > >>> danny > >>> > >>> > >> I modify my iscsi.conf by adding tags = 64 (and no tag). Now works fine, > >> about 43MB/s. Thank You very match. > >> RTFM :-) > >> But what means this parameter? > >> > > > > is the max number of commands that can be sent without waiting for ack. I set > > it > > too concervative :-( > > > I made many tests with different tags values and checked the writing > speed with dd. > 0 (default) -> ~850kB/s > 1 -> ~850kB/s > 2 -> ~6.5MB/s > 3 -> ~40MB/s > 4 -> ~49MB/s > 8 -> ~49MB/s > ... > > I think that NAS server sends ACK after 4 commands. Is it correct? in a simplistic way yes, it depends on how much memory the target has, the speed of its disks, and of course, the software :-) > Is it > possible that the NAS server modifies this behavior? Can I set tags at 4 > or is it smarter to keep it higher? > among many other things, it depends on how much memory you have, but I would set it somewhat higher, 8 or 16. try running several dd's simultaneously. danny
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?E1LLB0M-000OZp-Ms>