I was under the same impression - using a small portion of the SSD via partitioning (in my case - 30 gigs out of 240) would have the same effect as activating the HPA explicitly. Am I wrong? On Nov 7, 2013, at 8:16 PM, james@xxxxxxxxxxxx wrote: > On 2013-11-07 17:47, Gruher, Joseph R wrote: > >> I wonder how effective trim would be on a Ceph journal area. >> If the journal empties and is then trimmed the next write cycle should >> be faster, but if the journal is active all the time the benefits >> would be lost almost immediately, as those cells are going to receive >> data again almost immediately and go back to an "untrimmed" state >> until the next trim occurs. > > If it's under-provisioned (so the device knows there are unused cells), the device would simply write to an empty cell and flag the old cell for erasing, so there should be no change. Latency would rise when sustained write rate exceeded the devices' ability to clear cells, so eventually the stock of ready cells would be depleted. > > FWIW, I think there is considerable mileage in the larger-consumer grade argument. Assuming drives will be half the price in a years time, so selecting devices that can last only a year is preferable to spending 3x the price on one that can survive three. That though opens the tin of worms that is SMART reporting and moving journals at some future point mind. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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