> On Wed, May 29, 2002 at 08:07:58PM +0200, Anders Widman wrote: >> > On Wed, May 29, 2002 at 02:16:44PM +0200, Anders Widman wrote: >> What exactly shown in those diagrams? :) > It's trying to answer the question 'how does io to a volume slow down > if I take a snapshot'. The *overhead* is plotted on the vertical scale, > in terms of the time taken to do the operation with no snapshot. > So if I use a chunk size of 16k we see that LVM2 has an overhead of > 0.23, ie. the 'dbench 2' operation on a freshly snapshotted origin > will take 1.23 times as long compared to the snapshot not being > present. EVMS on the other hand takes 7.84 times as long. > If you find the numbers confusing just look at the raw results in the > first table. If you use 8k chunk sizes with EVMS expect 'dbench 2' to > take ~227 seconds compared to LVM2's ~15. >> > LVM2 by default uses the same metadata format as LVM1, so there really >> > isn't any conversion procedure. So try LVM2 for a bit, if you don't >> > like it (unlikely) revert to LVM1. Please note that metadata backups >> > and archives are held in a very different form. >> >> So I can just install LVM2 and continue as usual, and switch back if I >> get into trouble? > Yes. >> And, what if I get into trouble? I can not backup >> all data. There is not enough space for that. > What happens if you get in trouble with LVM1 ? If that data is > important you should really back it up, all drives fail eventually. True. Backups would be great, but, I have almost 1TB of data, and there is difficult to find a costworthy sollution. Actually I have had very bad luck with some of my drives. During a crash, probably a electric surge or something, 4 out of 14 drives got severe read/write errors. I could, however, rebuild data using reiserfs tools. If there were errors in the logical volume management, things might be more difficult to repair? >> >> Also, is it possible to convert (with and LVM version) a spanded >> >> volume to a striped volume? >> >> > Not until we get the new pvmove infrastructure. >> >> So, when newer pvmove tools develops it would be possible to convert >> a spanned volume to a sriped (RAID0 or 5?) volume without loosing data? > RAID5 is probably 6 months away, but I would hope to be able to remap > a linear volume to a striped volume in the next month or so. Ok. I'll wait for the RAID 5, as it would give me the redundancy I need. //Anders > - Joe > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
