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.
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.
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.
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.
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