[zfs-discuss] ZFS checksums - block or file level
I am trying to understand if zfs checksums apply at a file or a block level. We know that zfs provides end to end checksum integrity, and I assumed that when I write a file to a zfs filesystem, the checksum was calculated at a file level, as opposed to say, a block level. However, I have noticed that when I create an emulated volume, that volume has a checksum property, set to the same default as a normal zfs filesystem. I can even change the checksum value as normal, see below: # /usr/sbin/zfs create -V 50GB -b 128KB mypool/myvol # /usr/sbin/zfs set checksum=sha256 mypool/myvol Now on this emulated volume, I could place any number of structures that are not zfs filesystems, say raw database volumes, or ufs, qfs, etc. Since these do not perform end to end checksums, can someone explain to me what the zfs checksum would be doing at this point? This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS checksums - block or file level
On 2/1/07, Nathan Essex <[EMAIL PROTECTED]> wrote: I am trying to understand if zfs checksums apply at a file or a block level. We know that zfs provides end to end checksum integrity, and I assumed that when I write a file to a zfs filesystem, the checksum was calculated at a file level, as opposed to say, a block level. ZFS checksums are done at the block level. End to end checksum integrity means that when the actual data reaches the application from the platter, we can guarantee to a very high certainty that the data is uncorrupted. Either a block level checksum or a file level checksum will suffice. -- Regards, Jeremy ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS checksums - block or file level
ZFS checksums are at the block level. Nathan Essex wrote On 02/01/07 08:27,: I am trying to understand if zfs checksums apply at a file or a block level. We know that zfs provides end to end checksum integrity, and I assumed that when I write a file to a zfs filesystem, the checksum was calculated at a file level, as opposed to say, a block level. However, I have noticed that when I create an emulated volume, that volume has a checksum property, set to the same default as a normal zfs filesystem. I can even change the checksum value as normal, see below: # /usr/sbin/zfs create -V 50GB -b 128KB mypool/myvol # /usr/sbin/zfs set checksum=sha256 mypool/myvol Now on this emulated volume, I could place any number of structures that are not zfs filesystems, say raw database volumes, or ufs, qfs, etc. Since these do not perform end to end checksums, can someone explain to me what the zfs checksum would be doing at this point? This message posted from opensolaris.org ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS checksums - block or file level
Neil Perrin wrote: ZFS checksums are at the block level. This has been causing some confusion lately, so perhaps we could say: ZFS checksums are at the file system block level, not to be confused with the disk block level or transport block level. -- richard ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS checksums - block or file level
Richard Elling wrote: Neil Perrin wrote: ZFS checksums are at the block level. This has been causing some confusion lately, so perhaps we could say: ZFS checksums are at the file system block level, not to be confused with the disk block level or transport block level. Saying that ZFS checksums are at the file system block level is also confusing since zvols have checksums too. May be it is better to say that ZFS checksums are at the zpool block level because zpool is the place where all blocks either from file system or zvol are stored. Victor ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] ZFS checksums - block or file level
Victor Latushkin wrote: Richard Elling wrote: Neil Perrin wrote: ZFS checksums are at the block level. This has been causing some confusion lately, so perhaps we could say: ZFS checksums are at the file system block level, not to be confused with the disk block level or transport block level. Saying that ZFS checksums are at the file system block level is also confusing since zvols have checksums too. May be it is better to say that ZFS checksums are at the zpool block level because zpool is the place where all blocks either from file system or zvol are stored. Victor zpool block level makes the most sense to me, as a new ZFS user (long time list lurker). -- Dave ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
