> > We need to install the OS on the 3TB harddisks that come with our Dell > servers. (After many attempts, I've discovered that Dell servers won't allow > attaching an external harddisk via the PCIe slot. (I've tried everything). ) > > But, must I therefore sacrifice two hard disks (RAID-1) for the OS? I don't see > why I can't just create a small partition (~30GB) on all 6 of my hard disks, do a > software-based RAID 1 on it, and be done. > > I know that software based RAID-5 seems computationally expensive, but > shouldn't RAID 1 be fast and computationally inexpensive for a computer > built over the last 4 years? I wouldn't think that a CEPH systems (with lots of > VMs but little data changes) would even do much writing to the OS > partition....but I'm not sure. (And in the past, I have noticed that RAID5 > systems did suck up a lot of CPU and caused lots of waits, unlike what the > blogs implied. But I'm thinking that a RAID 1 takes little CPU and the OS does > little writing to disk; it's mostly reads, which should hit the RAM.) > > Does anyone see any holes in the above idea? Any gut instincts? (I would try > it, but it's hard to tell how well the system would really behave under "real" > load conditions without some degree of experience and/or strong > theoretical knowledge.) Is the OS doing anything apart from ceph? Would booting a ramdisk-only system from USB or compact flash work? If the OS doesn't produce a lot of writes then having it on the main disk should work okay. I've done it exactly as you describe before. James _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |