firewire disk spindown and other questions
simokawa at sat.t.u-tokyo.ac.jp
Mon Aug 18 22:06:51 PDT 2003
At Wed, 13 Aug 2003 21:58:14 -0700 (PDT),
<kyriazis at meer.net> wrote:
> Hello freebsd-firewire.
> I am new to freebsd, and I am planning on changing my file
> server from linux to freebsd.
> At the same time I would also like to move to firewire
> (from ide). I don't have large bandwidth requirements, so I'm
> just assuming that I'm not going to get too much lower performance.
> One basic question that I have is: Is it possible to set an
> automatic spindown of my firewire drives? I looked at the camcontrol
> manpage, but it doesn't say anything interesting.
freebsd-scsi should be the better place to ask this question.
There might be a mode page to control the automatic spindown but
I don't know.
> I am planning on setting up a raid-5 array (on firewire). Are there
> any issues that I should be aware of?? Since I haven't tried
> firewire yet, and I am (slightly) worried about performance, I wonder
> if putting all drives on one chain will give me problems. Would
> splitting drives over multiple firewire busses on the same card help
> any, or would I have to get multiple firewire cards to increase
> performance? Note, this is a server machine, so I'll only be accessing
> data through 100Mbit ethernet via samba.
Because ports share the bandwidth of the bus, you need another
card(chip) to increase bandwidth. You can have only a bus by a chip
even if it has multiple ports.
I got about 32MB/s for a drive and 40 MB/s for two drives on a same bus
under sequential read.
Also, you could notice performance decreasing for buses which have
large number of nodes because of arbitration gap count increasing.
> Also, I was wondering if there are problems with the order firewire
> clients are brought up in the bus. Will they come up as different
> each time I boot up? Ie, if I have 2 disks, coming up as da0 and da1,
> will the same disk come up as da0? Or will I have cases where one
> disk will come up as da0, then after a reboot the other disk will come
> up as ad0? If that is in fact the case, will that cause problem with
> vinum identifying which disk is which, or will it work because of the
> labels vinum puts on the disks themselves?
If you plan to use FreeBSD-5.X, geom_vol_ffs kernel module would help.
It wires down the specific UFS partition to specific device name.
If you don't mind to apply a patch to sbp.c, you can hard-code
EUI64->target id mapping table into the source code.
The biggest problem for wire-down in SBP is that SBP has (64+48)bit
identifier for the device but CAM cannot handle such big number.
So we have to map the device to small target numbers sequentially.
> Thank you!!
/\ Hidetoshi Shimokawa
\/ simokawa at sat.t.u-tokyo.ac.jp
PGP public key: http://www.sat.t.u-tokyo.ac.jp/~simokawa/pgp.html
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