>Number: 182818 >Category: kern >Synopsis: Slow writes to AHCI SATA on Soekris net6501 (Intel EG20T) in >*BSD >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Oct 08 00:40:00 UTC 2013 >Closed-Date: >Last-Modified: >Originator: Adam McDougall >Release: 10.0-ALPHA2 >Organization: >Environment: FreeBSD hoegaarden 10.0-ALPHA2 FreeBSD 10.0-ALPHA2 #0 r255793: Sun Sep 22 17:05:25 EDT 2013 root@build9:/usr/obj/proto/src10/src/sys/AMD64-10 amd64 >Description: I discovered these symptoms initially on 9.x, and this weekend upgraded to 10 just to check for improvement.
The total AHCI SATA write speed on the net6501 (*BSD only?) has a strange 20MB/sec limitation but reads can go over 100MB/sec. If I write to one disk I get 20MB/sec, but if I write to both SATA disks (such as mirroring) I get 10MB/sec each for a total of 20. Writes are equally slow on a high end SSD. Both someone running OpenBSD and I running FreeBSD reported the same symptoms to the soekris-tech mailing list and received no useful replies towards getting that problem solved. I believe I duplicated the symptoms on NetBSD. I tested the write speed briefly with Linux and it did not appear to have the 20MB/sec limitation (I wrote enough data that I was satisfied it could not be cached in ram). I did confirm it was using MSI of some form with boot -v. The disks I tested with are fine in normal computers. I have three of these systems. They are all acting as firewalls where write speed is not critical to operation, although one is considered a spare that I can experiment with. They are not my property so I don't think I can mail one for personal inspection. >How-To-Repeat: Use something (dd?) to write to the raw devices or to a filesystem, use gstat -I 50000 to confirm a total limitation of 20MB/sec disk IO whether it is to one disk or two (10 each). >Fix: >Release-Note: >Audit-Trail: >Unformatted: _______________________________________________ freebsd-bugs@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
