I am new to OSOL/ZFS myself -- just placed an order for my first system last week. However, I have been reading these forums for a while - a lot of the data seems to be anecdotal, but here is what I have gathered as to why the WD green drives are not a good fit for a RAIDZ(n) system.
(1) They seem to have a firmware setting (that may not be modified depending on revision) that has to do with the drive "parking" the drive after 8 seconds of inactivity to save power. These drives are rated for a certain number of park/unpark operations -- I think 300,000. Using these drives in a NAS results in a lot of park/unpark. (2) They are big and slow. This seems to be a very bad combination for RAIDZ(n). I have seen people report resilvering times of 2 to 4 days. I am not sure how much that impact performance. But that can be a long time to run in a degraded state for some people. I don't know how the resilvering process works - so I don't know if it is a ZFS issue or not.. Regardless of the drive speed it seems like more than 2 days to write 1 to 2 TB worth of data is ridiculous - but no one seems to complain that it is ZFS's fault - so there must be a lot involved in resilvering that I don't understand. I think that small and slow would be OK - if you had 500GB green drives you might be fine.. But people tend to look at the green drives because they have so much capacity for the money - so I haven't seen anyone say that a Green 500GB drives work well. (3) They seem to have a lot of platters.. 3 or 4. More platters == more heat == more failure... apparently. (4) The larger WD drives are 4k sectors which is fine by itself, but because windows XP doesn't like that they have some weird firmware stuff in there to emulate different sector sizes. I am not sure it can be disabled or if it is in fact a problem, but I have seen it mentioned in various gripes. Like I said, I am no expert. But these factors made me choose 1TB samsung spinpoints for my Raidz2 config that I just ordered. I may look into some of these green drives for a secondary mirror zpool at some point - I have some items where I don't need need great redundancy and can trade off speed for cost. -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
