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Sybase disk mirror
I have configure the disk mirror on my Sybase machine, How do I monitor the progress of mirror? how will I notice my mirror going down or issue occured ?
ASKER
Hi,'
Thanks for this very long explicit explanation, Yes I'm 100% belongs to Mcsft, It was 10 years back my day with Oracle RDB running on VMS and since then I'm dedicated my self with Mssql + windows :(.
well what I'm trying to say with "progress" is just need to know if this sybase mirror provide us with any command or sp which we can monitor how mirror works at least we know on what command being mirrored to mirror device, if u said we can 100% trust on sybase mirror, then I have niothing much to say :)
< If the disk is unmirrored, all writes to the failed disk will fail, and users will be affected.> is this means we have to immediately to remirror to avoid from downtime ?
do you know when should I activate the mirror device? is that only upon primary device failed/corrupted is that anyway which mirror will take over immediately upon primary crashed?
Thanks for this very long explicit explanation, Yes I'm 100% belongs to Mcsft, It was 10 years back my day with Oracle RDB running on VMS and since then I'm dedicated my self with Mssql + windows :(.
well what I'm trying to say with "progress" is just need to know if this sybase mirror provide us with any command or sp which we can monitor how mirror works at least we know on what command being mirrored to mirror device, if u said we can 100% trust on sybase mirror, then I have niothing much to say :)
< If the disk is unmirrored, all writes to the failed disk will fail, and users will be affected.> is this means we have to immediately to remirror to avoid from downtime ?
do you know when should I activate the mirror device? is that only upon primary device failed/corrupted is that anyway which mirror will take over immediately upon primary crashed?
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ASKER
very gud explanation indeed
The deterministic question is:
If a disk device (a mirror is just another disk device) goes down, an error will be logged. If the disk is mirrored, there is no effect on the users, the mirror will keep going, and you can re-create the new disk somewhere else. If the disk is unmirrored, all writes to the failed disk will fail, and users will be affected.
I am not sure what you mean by "progress" of the mirror. The mirror is active 100% of the time, all writes to the device will be duplicated to the mirror device. It is only when you start a new mirror that there is an initial witing to it, to make it a mirror, a "catch-up" period.
For monitoring the activity on both the device and the mirror device, use sp_sysmon. Or any one of the available good 3rd party monitoring tools.
I am not saying that you should not use Sybase mirroring, but you should evaluate doing the mirroring at the Disk Controller or Volume Manager level. This is much faster, because it is middleware, and it releases ASE from the task, which allows those free cycles to be used for the other things ASE does. Sybase mirroring was essential in the old days, before Volume Managers were available, but since their advent, it is the slower choice. Additionally, with a VM, you can configure and re-configure the entire disk array for the server (or several servers), not just the Sybase devices. Sybase mirrors remain essential and are excellent for other purposes (not relevant to this question).