On Tue, Mar 12, 2013 at 4:30 AM, Arun Khan <knura9 at gmail.com> wrote: > On Thu, Mar 7, 2013 at 12:07 AM, Gordon Messmer wrote: > > On 03/06/2013 08:35 AM, Arun Khan wrote: > > > >> Any preference between 1 and 2 above. > > > > Based on about 10 years of running a hundred or so systems with 3ware > > controllers, I would say that you're better off with an LSI MegaRAID > > card, or with Linux software RAID. 3ware cards themselves have been the > > most problematic component of any system I've run in my entire > > professional career (starting in 1996). Even very recent cards fail in > > a wide variety of ways, and there is no guarantee that if your array > > fails using a controller that you buy now that you'll be able to connect > > it to a controller that you buy later. > > @ Gordon - thanks for sharing this piece of info! In case of RAID > card failure, it is important to be able to recover the data (RAID > device) with a compatible replacement. Are the LSI MegaRAID > controller more reliable in this respect? > I've not had any MegaRAID controllers fail, so I can only say they've been reliable thus far! > > > At this point, I deploy almost exclusively systems running Linux with > > KVM on top of software RAID. While I lose the battery backed write > > cache (which is great for performance unless you sustain enough writes > > to fill it completely, at which point the system grinds nearly to a > > halt), I gain a consistent set of management tools and the ability to > > move a disk array to any hardware that accepts the same form factor > > disk. The reliability of my systems has improved significantly since I > > moved to software RAID. > > Software RAID is an option but I don't think hot swap is possible > without some tinkering with the mdadm tool a priori. > Hot swap really depends on what your HBA or RAID controller supports. You start by failing/removing the drive via mdadm. Then hot remove the disk from the subsystem (ex: SCSI [0]) and finally physically remove it. Then work in the opposite direction ... hot add (SCSI [1]), clone the partition layout from one drive to the new with sfdisk, and finally add the new disk/partitions to your softraid array with mdadm. You must hot remove the disk from the SCSI subsystem or the block device (ex: /dev/sdc) name is occupied and unavailable for the new disk you put in the system. I've used the above procedure many times to repair softraid arrays while keeping systems online. [0] https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/removing_devices.html [1] https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/adding_storage-device-or-path.html The systems will go to client site (remote), prefer to keep the > support calls to remove/replace hardware activity :( > > Thanks, > -- Arun Khan > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -- ---~~.~~--- Mike // SilverTip257 //