On 11/04/2020 10:47 PM, Valeri Galtsev wrote: > >> On Nov 4, 2020, at 9:21 PM, John Pierce <jhn.pierce at gmail.com> wrote: >> >> is it RAID 0 (striped) or raid1 (mirrored) ?? >> >> if you wrote on half of a raid0 stripe set, you basically trashed it. >> blocks are striped across both drives, so like 16k on the first disk, then >> 16k on the 2nd then 16k back on the first, repeat (replace 16k with >> whatever your raid stripe size is). >> >> if its a raid 1 mirror, then either disk by itself has the complete file >> system on it, so you should be able to remirror the changed disk onto the >> other drive. you MUST do that re-mirror because your two disks are no >> longer identical, and reads will alternate between them, so some reads will >> get new data and others will get old data, which will be highly chaotic. >> > John, I figure, BIOS RAID is essentially software RAID (handled by Linux kernel’s md module, or whatever module's name is). I have a question then. If it were RAID-1, and one of the drives was mounted, would the kernel’s md (?) module recognize that the other drive is out of sync, - there should be timestamp when each of RAID members was last in sync/used. Right? Or I am mistaken? > > If I understand correctly, OP has, or rather had (uh-huh), RAID-0. > > Valeri > > PS. I thought I was wrong, but I was mistaken ;-) > >> >> On Wed, Nov 4, 2020 at 6:18 PM H <agents at meddatainc.com> wrote: >> >>> My computer running CentOS 7 is configured to use BIOS RAID0 and has two >>> identical SSDs which are also encrypted. I had a crash the other day and >>> due to a bug in the operating system update, I am unable to boot the system >>> in RAID mode since dracut does not recognize the disks in grub. After >>> modifying the grub command line I am able to boot the system from one of >>> the harddisks after entering the LUKS password, seemingly without any >>> problems but am obviously not running in RAID0 mode. When I booted in >>> single-disk mode I am sure there were some new files created on the single >>> SSD the system sees but I fairly quickly shut it down until this can be >>> fixed. >>> >>> >>> >>> My question is: once the operating system fix has been released and I can >>> once again boot in BIOS RAID0 mode and decrypting both SSDs (same password >>> entered only once of course), how will the BIOS RAID0 react? How will it >>> handle new files on one disk, altered timestamps etc.? >>> >>> >>> Thanks. >>> >>> _______________________________________________ >>> CentOS mailing list >>> CentOS at centos.org >>> https://lists.centos.org/mailman/listinfo/centos >>> >> >> -- >> -john r pierce >> recycling used bits in santa cruz >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> https://lists.centos.org/mailman/listinfo/centos > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos Gentlemen, I misspoke, it is RAID1, ie mirroring, not striping, RAID0. If it had been the latter, I would not have been able to boot from one of the two disks. With that said, I have now rebooted my system from one disk and am making a backup to a separate harddisk using dd. I am not sure how the BIOS RAID - don't know if it is hardware or software - will handle the difference between the two disks when I am being able to reboot again once the CentOS bug has been fixed...