From: Feizhou <fe...@gr...> - 2005-07-27 16:47:55
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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. |