On Dec 4, 2007 10:22 AM, Jc Polanycia <[EMAIL PROTECTED]> wrote: > > Off topic, as I seldom partition anything (unpartitioned drives > > perform best), but, you're setting yourself up for disaster using LVM > > (any corruption to the LVM layer is not recoverable... you'll loose > > everything... been there done that), and the performance is poor, and > > MD RAID5/6 devices can be grown (add more disks). > > > > Chris > > > > Fair enough. I appreciate the input because I haven't run across any > real-world stories about LVM corruption. I have personally encountered > corruption problems with RAID5/6 as well as problems with decreased > performance as a RAID5 structure gets more members added to it.
I saw some RAID6 issues last year, so I use RAID5... but recent tests have shown MD RAID6 as solid. "Decreased performance as more members get added to it"? Bull!!! I'm guessing you have another bottleneck that has led you to this conclusion. While the performance increase doesn't scale linearly as disks are added (some CPU verhead is added with each additional drive), the more disks, the better the performance. I'm sure there is some Amdahl's law limit to the increased performance scalability, but I run RAIDS up to 12 drives, and see performance added w/ each new member. > > Could you please provide me additional information about the circumstances > under which you had the LVM layer corrupt? Thanks. It's been too long, so, no, I can't. I vaguely remember something simple being overwritten in the LVM metadata, and there being no method to recover it (except from backup). I had similar issues with ReiserFS. While there were some provisions for recovery, they were insufficient. As FS'es go, Ext3 has the most bullet-proof recovery mechanisms when the metadata has been compromised. Realize that all the layers above the MD device, LVM and whatever FS, add more complexity and therefore decrease performance and reliability. Note that the metadata corruption I'm referring to is not a spindle failure issue: you can corrupt the metadata, and your RAID preserves the corruption! MD device metadata can be recreated if you know the incantation used to initially create the RAID (and it's usually simple enough that you can recreate the RAID on the fly from memory). So, I stick w/ Ext3 and MD. Chris > > -jc > -- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
