7.1 and mpt, slow writes

[Charles Sprickman]

Hi all,

I had this one figured out in 6.x, but I'm not seeing a similar fix in 
7.x.

I have a Dell Poweredge 860 with a Dell-branded LSI controller:

mpt0: <LSILogic SAS/SATA Adapter> port 0xec00-0xecff mem 
0xfe9fc000-0xfe9fffff,0xfe9e0000-0xfe9effff irq 16 at device 8.0 on pci2
mpt0: [ITHREAD]
mpt0: MPI Version=1.5.13.0
mpt0: Capabilities: ( RAID-0 RAID-1E RAID-1 )
mpt0: 1 Active Volume (2 Max)
mpt0: 2 Hidden Drive Members (10 Max)
...
mpt0:vol0(mpt0:0:0): Settings ( Hot-Plug-Spares High-Priority-ReSync )
mpt0:vol0(mpt0:0:0): Using Spare Pool: 0
mpt0:vol0(mpt0:0:0): 2 Members:
       (mpt0:1:32:0): Primary Online
       (mpt0:1:1:0): Secondary Online
mpt0:vol0(mpt0:0:0): RAID-1 - Optimal
mpt0:vol0(mpt0:0:0): Status ( Enabled )
(mpt0:vol0:1): Physical (mpt0:0:1:0), Pass-thru (mpt0:1:0:0)
(mpt0:vol0:1): Online
(mpt0:vol0:0): Physical (mpt0:0:32:0), Pass-thru (mpt0:1:1:0)
(mpt0:vol0:0): Online
da0 at mpt0 bus 0 target 0 lun 0
da0: <Dell VIRTUAL DISK 1028> Fixed Direct Access SCSI-5 device
da0: 300.000MB/s transfers
da0: 75340MB (154296320 512 byte sectors: 255H 63S/T 9604C)

Basic tests with dd and bonnie show that writes are much slower than 
reads:

[root at uniweb /jails]# dd if=/dev/zero of=foo count=1000M
^C1293952+0 records in
1293951+0 records out
662502912 bytes transferred in 97.712971 secs (6780092 bytes/sec)
[root at uniweb /jails]# dd if=foo of=/dev/null
1293952+0 records in
1293952+0 records out
662503424 bytes transferred in 5.065705 secs (130782076 bytes/sec)

Version 1.93d       ------Sequential Output------ --Sequential Input- 
--Random-
Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- 
--Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP 
/sec %CP
uniweb.bway.n 2016M   220  99  6744   2  5985   2   417  99 58007  14 
245.8   8
Latency             42611us     297ms    3053ms   24821us   43190us 
4987ms
Version 1.93d       ------Sequential Create------ --------Random 
Create--------
uniweb.bway.net     -Create-- --Read--- -Delete-- -Create-- --Read--- 
-Delete--
               files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP 
/sec %CP
                  16    65   0 +++++ +++   118   0    69   0 +++++ +++ 
127   0
Latency               332ms      36us     496ms     209ms      27us 
2164ms

In 6.x, I was able to resolve this by enabling the write cache on the 
drives via a loader tunable, "hw.mpt.enable_sata_wc".  That seems to be 
gone in 7.x.  Is there a new way to set this?  I see no mention of the wc 
options at all in the mpt manpage.

Also, do we have any way to monitor/manage these cards natively yet?

Thanks,

Charles

___
Charles Sprickman
NetEng/SysAdmin
Bway.net - New York's Best Internet - www.bway.net
spork at bway.net - 212.655.9344