As we all know, FreeNAS provides feature of auto zvol snapshot creation, but does it support auto zvol snapshot deletion, especially, I hope to have snapshot auto deletion when the containing zpool is reaching full.
Without such auto deletion feature, I'm afraid I'll be facing ENOSPC (no space error) all the time. Imaging, I have a 100GB zpool and create a solid 80G zvol on it; I use solid instead of sparse in order to guarantee that this zvol can always have a total of 80G available space. But, is such guarantee still true when I use zvol snapshot feature? Consider this, I take a snapshot this morning when the zvol is filled with 80G user data, then I go on modifying all data on this zvol. The question is, Can I still write 80GB new data on that zvol? If that snapshot is still preserved, it would cost total 160G space to accommodate my old 80G and new 80G of data, of course impossible.
So can I make a conclusion: If you do not have snapshot auto deletion facility, even a solid zvol cannot guarantee your space requirement. Right?
I know Windows NTFS Volume Shadow Copy(VSS) have such snapshot auto deletion feature. You designate a portion of partition space for VSS storage, 10G for example, then snapshoted data(old data) will not consume more than that. If it would exceed that, the oldest snapshot will be deleted automatically. I'd like to know whether such similar feature exist for FreeNAS or FreeBSD?
Thank you.
Without such auto deletion feature, I'm afraid I'll be facing ENOSPC (no space error) all the time. Imaging, I have a 100GB zpool and create a solid 80G zvol on it; I use solid instead of sparse in order to guarantee that this zvol can always have a total of 80G available space. But, is such guarantee still true when I use zvol snapshot feature? Consider this, I take a snapshot this morning when the zvol is filled with 80G user data, then I go on modifying all data on this zvol. The question is, Can I still write 80GB new data on that zvol? If that snapshot is still preserved, it would cost total 160G space to accommodate my old 80G and new 80G of data, of course impossible.
So can I make a conclusion: If you do not have snapshot auto deletion facility, even a solid zvol cannot guarantee your space requirement. Right?
I know Windows NTFS Volume Shadow Copy(VSS) have such snapshot auto deletion feature. You designate a portion of partition space for VSS storage, 10G for example, then snapshoted data(old data) will not consume more than that. If it would exceed that, the oldest snapshot will be deleted automatically. I'd like to know whether such similar feature exist for FreeNAS or FreeBSD?
Thank you.
