Hi David, Thanks for the info, it's very assuring to know that TRIM is not needed. We bought Samsung 830 256GB SSDs, and as I understood, they're very good, but their GC is only when the device is idling, and they will be installed on a DB server. I don't know if they'll be idle for long periods. Do you perhaps know if we need to over-provision modern SSDs like the Samsung 830's ? Thanks! Bar. On Wed, Jul 11, 2012 at 2:27 PM, David Brown <david.brown@xxxxxxxxxxxx> wrote: > On 07/11/2012 12:55 AM, Bar Ziony wrote: >> >> Hi, >> >> I wasn't able to find any information about it after searching for >> hours - Does mdadm supports sending the TRIM command to SSDs, if using >> the right filesystem with the 'discard' flag? >> If it does support it, from what kernel version it is? >> >> Thank you, >> Bar. > > > The big question here is /why/ would you want TRIM support? In many > circumstances it leads to slower operations, and for SSDs from the past > couple of years it is almost entirely superseded by the SSD's own garbage > collection. > > So while there certainly has been some work done on TRIM and md raid, it is > not a priority as it is of questionable benefit. You might find some > operations are a little faster for older SSDs if you use TRIM, but your > metadata operations will be a lot slower. > > Your best bet is just to make sure you only buy SSDs that are at least half > decent, and don't worry about TRIM. > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
