Date: Thu, 6 May 1999 15:02:38 -0500 (CDT) From: David Scheidt <dscheidt@enteract.com> To: Zhihui Zhang <zzhang@cs.binghamton.edu> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Copies of superblocks in FFS Message-ID: <Pine.NEB.3.96.990506145000.47110B-100000@shell-1.enteract.com> In-Reply-To: <Pine.GSO.3.96.990506145327.15238A-100000@sol.cs.binghamton.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, 6 May 1999, Zhihui Zhang wrote: :If the primary superblock (the second copy in cylinder group 0, at offset :8192+8192) is updated and other superblocks are not updated at the same :time, how can any of other copies be used to restore file system in case :that the primary copy is corrupted somehow? If so, the performance will :be degraded. Most of what is in the superblock is static, and doesn't change from filesystem creation time. The things that don't can be created from the disk, at fsck time. fsck -b has saved a lot of filesystems, and is clearly worth a few wasted blocks. : :Also, except for the root filesystem (/), all other filesystems (/var, :/usr, etc.) do not have the (boot code + disklabel) installed, these space :are also wasted (8192 bytes for each non-root filesystem). It is very handy to be able to make a filesytem bootable after it has been created. Much easier than dumping the filesytem, remaking the filesytem, and then restoring it. I'll pay 16K per filesystem for this. : :BTW, the hard disks are more stable nowadays and any bad sectors may have :been hidden by the disk controllers (the filesystem does not have to deal :with them). Panics still can leave the primary superblock hosed. Trust me. David Scheidt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.NEB.3.96.990506145000.47110B-100000>