> -----Original Message----- > From: CentOS [mailto:centos-bounces at centos.org] OnBehalf Of Gregory P. > Ennis > Sent: Sunday, February 19, 2017 12:31 PM > To: centos at centos.org > Subject: Re: [CentOS] usb drives & Orico ORICO9548U3-BK > > > > > > I decided to build an archive server for thepurpose of backing up > > other fedora/centos desktops at theoffice. I built a machine and > > have installed Centos 7.3 on it with all updatescurrent. I also > > purchased a 3.0 usb sata drive cabinet (OricoORICO 9548U3-BK) and > > installed two 5T black WDdrives. There was no problem installing > > the usb cabinet or the drives. Iformatted each drive with xfs as > > /dev/sdc and /dev/sdd, and then combined theminto a software mirrored > > raid with mdadm as /dev/md0. > > I've always thought that the perceived wisdom is tonot try and do software > raid across USB - especially when both drives are atthe other end of the > same USB cable. Sure USB 3 is faster and there's abetter chance it will appear > to work at a reasonable speed, but it's notsomething I would contemplate. > > > > > Everything was working perfectly until Iremoved the terminal, > > keyboard and mouse and tried to reboot themachine. It took a while > > to figure out, but when the mouse and keyboardwere removed the boot > > process assigns the usb drives differentlywhich makes /dev/md0 > > created by mdadm fail. > > Which means that the drive letters are explicitlymentioned in > /etc/mdadm.conf - you can change it to be wildcardedor leave mdadm to > figure it all out itself. See 'manmdadm.conf'. > > > > > My fstab file looks like : > > > > /dev/mapper/centos_poar-root / xfs defaults 0 > > 0 > > UUID=f915a354-28bf-4110-bec9-3767ef1fe52c/boot xfs defaults 0 > > 0 > >/dev/mapper/centos_poar-home /home xfs defaults 0 > > 0 > >/dev/mapper/centos_poar-u /u xfs defaults 0 > > 0 > >/dev/mapper/centos_poar-swap swap swap defaults 0 > > 0 > >/dev/sda /u0 btrfs defaults 0 > > 0 > > # entries below were combined into one mirroredraid system > #/dev/sdc > >/u1 xfs defaults 0 > > 0 > >#/dev/sdd /u2 xfs defaults 0 > > 0 > >/dev/md0 /u1 xfs defaults 0 > > 0 > > Another likely issue is that you explicitly mention/dev/sda in the fstab - if the > drives are re-ordered, then /dev/sda will not bewhat you think it is. It's a > much better idea to use UUIDs when mounting drives.You can find the UUID > with > > lsblk --fs /dev/sda > > BTW, are you really using partitionless disks - isit really /dev/sda and not > /dev/sda1 ? > > > > > > > This works perfectly when a usb mouse and a usbkeyboard are attached, > > but when I remove the mouse and keyboard thesystem will not boot > > because the usb drives are relabeled as/dev/sda and /dev/sdb. > > I would have thought that any SATA drives would havebeen processed > before the USB drives - certainly it looks that wayon my system. Try going > through the output of dmesg to see if you can seewhat is really happening > when in the boot sequence. > > > > > > > My thought is that if I could force the usbdrives to be labeled as > > /dev/sdc and /dev/sdd whether the mouse andkeyboard are attached or > > not, I might be able to fix the problem > > It's much easier to make sure you don't explicitlyuse drive letters - because, > as you've found out, they can change. Usefilesystem labels or UUIDs or disk > IDs. The disk IDs can be found in /dev/disk/by-idand they should remain the > same. > > P. > >----------------------------------------------------------------- > > Pete, > > Thank you for such excellent help; I appreciate yourwisdom and challenges. > The machine I am working on is still at the 'lab'stage so everything can be > changed at this point. I don't have the benefit of much 'perceivedwisdom' in > that most of my knowledge comes from mistakes I havemade or mistakes > others on this list have made that Ican learnfrom. So thanks again. > > Here are some of my thoughts... right or wrong. > > #1. 3.0 USB drives > I originally performed some testing on a small usbpassport 3T drive and was > amazed by the response and access times. I stumbled across the Orico > cabinet during a NewEgg search, and decided to giveit a try. I was even > more impressed with the response and accesstimes. I decided to attempt a > mdadm raid on the the Orico and everything hasworked better than > expected except for the problems I have had withdevice > assignments. I did have an electrical failure at my home related to > weather of which the ups powered down after 30minutes that caused one > of the raid 5T drives to become corrupted. I reformatted the drive and > rebuilt the raid with mdadm, and everything worked alot better than I > expected. Iwill only be using this system to store *.tar.gz backup files from > other systems. What should cause me to fear the USB 3.0 connection. > > #2. /etc/mdadm.conf > The tutorials I read about how to use mdadm did notinclude mdadm.conf, > and this was not created when I installedmdadm. I will take a look at the > man pages.... thank you. > > #3. UUID's > Thanks for the suggestion to use names instead ofdevice addresses and > how to get the names with lsblk --fs /dev/sda. Using this should fix > my problem of reassignment device names at boottime. Thanks much!!! > > #4. Partitionless disks > I orginally installed Centos 7.3 on an SSD, and theninstalled the hard drives > subsequently. I noticed that I gained quite a bit of disc space by not using a > partition. Since the files I will be storing on these discs are large and will only > be accessed for archive purposes I wanted > to use as much of the disk as possible. The original google searches > I made related to using a partitionless disk did notgive me compelling rational > to use a partition, however I would surely like tohear from you and others > about this. > > > Thanks again for your help, and instruction!!!!! > I kinda did the same thing as you. I bought a 4TB WDElements. Disabled the sleep timer. I use UrBackup to backup two local machines, one remote,to my CentOS server. The WD Elements is backing up the CentOS server as wespeak (since 9:00AM this morning). I use a rsync script I found,https://github.com/laurent22/rsync-time-backup I started with REAR, but it created a 1TB tar.gz file soI went with the rsync script. Had to remove the --one-file-system arg.