@Jonathan, I completely agree on the SSD failure. I wasn't suggesting that better write endurance made them impervious to failures, just that I read a few articles from ~3-5 years back saying that RAID5 or RAID6 would destroy your SSDs and have a really high probability of all SSDs failing at the same time as the # of writes were equal on all SSDs in the RAID group. I think that's no longer the case and RAID6 on SSDs is fine. I was looking for examples of what others have done: RAID6, using GPFS data replicas, or some other thing I don't know about that better takes advantage of SSD architecture. Background - I am a storage noob
Also is the @Jonathan proper list etiquette? Thanks everyone to great advice I've been getting. Thank you, Brian On Sun, Jul 17, 2016 at 5:49 PM, Jonathan Buzzard <[email protected]> wrote: > On 17/07/16 03:56, Brian Marshall wrote: > >> When setting up SSDs to be used as a fast tier storage pool, are people >> still doing RAID6 LUNs? I think write endurance is good enough now that >> this is no longer a big concern (maybe a small concern). I could be >> wrong. >> >> I have read about other products doing RAID1 with deduplication and >> compression to take less than the 50% capacity hit. >> >> > There are plenty of ways in which an SSD can fail that does not involve > problems with write endurance. The idea of using any disks in anything > other than a test/dev GPFS file system that you simply don't care about if > it goes belly up, that are not RAID or similarly protected is in my view > fool hardy in the extreme. > > It would be like saying that HDD's can only fail due to surface defects on > the platers, and then getting stung when the drive motor fails or the drive > electronics stop working or better yet the drive electrics go puff > literately in smoke and there is scorch marks on the PCB. Or how about a > drive firmware issue that causes them to play dead under certain work > loads, or drive firmware issues that just cause them to die prematurely in > large numbers. > > These are all failure modes I have personally witnessed. My sample size > for SSD's is still way to small to have seen lots of wacky failure modes, > but I don't for one second believe that given time I won't see them. > > JAB. > > -- > Jonathan A. Buzzard Email: jonathan (at) buzzard.me.uk > Fife, United Kingdom. > _______________________________________________ > gpfsug-discuss mailing list > gpfsug-discuss at spectrumscale.org > http://gpfsug.org/mailman/listinfo/gpfsug-discuss >
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