On Thu, 10 Jun 2010 17:22:19 -0400 Miles Fidelman <mfidelman@xxxxxxxxxxxxxxxx> wrote: > > Do you currently have a write intent bitmap in the array? I think it can > > reduce the need for recovery by an order of magnitude in some cases. Check > > man mdadm for --bitmap if you don't use it yet. > > > Just went through the process of turning it on for all my arrays. > Incredibly painless and quick. Now I get to wait and see if it helps > the next time I have a crash/reboot event. I assume you went with "internal" bitmap, in which case if you notice that write speed on the arrays became significantly lower, the first thing you should look at is increasing the --bitmap-chunk size (I use 131072). It is possible to use an external bitmap on an independent device (which has almost zero performance impact), but in this case it could be non-trivial to 100% ensure that such a device is mounted and accessible at the moment during boot-up when md arrays are being started, especially if one of those arrays also hosts the root FS. -- With respect, Roman
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