<div dir="ltr"><div>Fellow GPFS Users,</div><div><br></div><div>I have a silly question about file replicas... I've been playing around with copies=2 (or 3) and hoping that this would protect against data corruption on poor-quality RAID controllers.. but it seems that if I purposefully corrupt blocks on a LUN used by GPFS, the "replica" doesn't take over, rather GPFS just returns corrupt data. This includes if just "dd" into the disk, or if I break the RAID controller somehow by yanking whole chassis and the controller responds poorly for a few seconds.</div><div><br></div><div>Originally my thinking was that replicas were for mirroring and GPFS would somehow return whichever is the "good" copy of your data, but now I'm thinking it's just intended for better file placement.. such as having a near replica and a far replica so you dont have to cross buildings for access, etc. That, and / or, disk outages where the outage is not corruption, just simply outage either by failure or for disk-moves, SAN rewiring, etc. In those cases you wouldn't have to "move" all the data since you already have a second copy. I can see how that would makes sense..</div><div><br></div><div>Somehow I guess I always knew this.. but it seems many people say they will just turn on copies=2 and be "safe".. but it's not the case..</div><div><br></div><div>Which way is the intended?</div><div>Has anyone else had experience with this realization?</div><div><br></div><div>Thanks,</div><div>-Zach</div><div><br></div><div><br></div>-- <br><div class="gmail_signature">Zach Giles<br><a href="mailto:zgiles@gmail.com" target="_blank">zgiles@gmail.com</a></div>
</div>