On Thu, 2005-07-28 at 00:48 +0800, Feizhou wrote:
> Ming Zhang wrote:
>
> >On Thu, 2005-07-28 at 00:24 +0800, Feizhou wrote:
> >
> >
> >>>>>>I have a question for you. I want to use iscsi array
> >>>>>>to store database data file. I hope I can get some
> >>>>>>kind of redundency (RAID) as well as dynamic increase
> >>>>>>disk space without shuting down the database to
> >>>>>>rebuild the array. The database will have transactions
> >>>>>>all the time and can't be shutdown.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>i am thinking if possible to have
> >>>mysql + xfs + open-iscsi + iet + lvm + md. so if need larger size, just
> >>>add another software raid to vg and then do lvextend, then do rescan on
> >>>iet (need develop), then do a xfs online resize?
> >>>
> >>>
> >>>
> >>>
> >>xfs the fs? Ugh. ext3 with data=journal would be better in case of a
> >>crash or what ever.
> >>
> >>
> >can ext3 do online resize? i am not sure.
> >
> >
> yup. latest centos4.1 does it for example.
cool. thx
>
> >
> >
> >>unless you have free hotswap SCSI bays available, adding another
> >>software raid will have to mean another box with iet.
> >>
> >>
> >but raid5 can not dynamic add disk and expand size right?
> >
> >
> >
> no, hence the need for lvm...but at the same time, lvm does not tolerate
> disk loss.
so that is why i am thinking lvm on top of several raid5 or 1
>
> >
> >
> >>At same blinking time, lvm does not tolerate losing physical volumes so
> >>if a iet box goes down....
> >>
> >>
> >iet is on top of lv, so even iet box crash, hopefully lvm is still
> >there.
> >
> >
> >
> you still need lvm on the database box itself to do dynamic resizing.
why? i resize the lv iet exports and then ini side see new size scsi
disk.
>
> >
> >
> >>very murky this one
> >>
> >>
> >
> >:P any suggestion?
> >
> >
> i had a hard think on this one...linux lvm don't do fault tolerance but
> md does...so where do you use these pieces on the initiator box and or
> the target box and how to combine them is a bit sketchy at the moment.
we need a complete solution...
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