-------- Original Message --------
On 5/10/07, Al Hopper <[EMAIL PROTECTED]> wrote:
My personal opinion is that USB is not robust enough under (Open)Solaris
to provide the reliability that someone considering ZFS is looking for.
I base this on experience with two 7 port powered USB hubs, each with 4 *
2Gb Kingston flash drives, connected via 2 ports to a Solaris (update 3)
desktop box which runs ZFS on two internal 500Gb drives. I see about 24
to 28Mb/Sec (bytes) maximum of bandwidth over each USB bus. One time,
after disconnecting one hub (to show someone the hub with 4*USB drives) it
hung the OS and reset the box. A subsequent import of the ZFS volume that
was disconnected, failed. (Yes it was exported, but failed to import).
So my take on USB is ... it's not sufficiently robust - and a USB related
failure is likely to cause loss of the entire ZFS dataset; i.e., its
likely to trash more that one drive in a raidz config.
I am interested in your this comment on USB. But it seems too general
and not helpful to solve problems. Several issues have been mixed
together which may not necessarily be USB's fault. If you believe there
is a USB issue, a better practice is to file a bug. And please make sure
the problem is reproducible and be detailed in problem description. :-)
I play with USB devices a lot and seldom see hotplugging hangs a system.
The hang looks very exceptional to me. Could you experiment more with
the devices and combinations of filesystem configuration? e.g., if you
put on the drives UFS instead of ZFS, would it hang? Is there a way that
you can reproduce the hang much more reliably?
Another question is if you are using ZFS on USB drives, the system hangs
due to non-usb related reason and you reset the box, can data integrity
on the USB drives be ensured?
Yet another question is if you are using non-USB drives, the system
hangs due to whatever reason and you reset the box, can data integrity
on the non-USB drives be ensured? And how, by SW or HW?
We need to think of the questions and make clear if such kind of data
loss is particular to USB or not before coming to a conclusion too quickly.
I'd be interested in hearing other opinions on USB connected drives
under (Open)Solaris ....
Any bus can have errors. USB is nothing particular, just the chance of
encountering errors is bigger since USB device is cheap. But isn't the
file system expected to handle possible errors?
Thanks,
Sophia
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
