Drobo

WD 2TB Green fast enough for DroboS?

Hi - I know there have been some other questions regarding slower drives used in the Drobo S but I’m wondering if anyone has experience with the WD green drives specifically? I had intended to get the WD Black series but was talked out of it by the sales person who said there was no point putting a faster drive in the Drobo…I mentioned it would be for using video and over e-sata but they were adamant…any thoughts?

I took their advice and am in the process of copying to files over and am only seeing 30mb/s write with FW800 (reading from a Lacie rugged 500gb FW800)… This does seem slow but I don’t have an e-sata PCI card yet to test whether it’s the interface, the drives, or simply Drobo…

thanks in advance
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apparently for the pro (and therefore also the elite) 7200rpm drives DO make a difference (im not sure if its much of a difference).

From what i understand the processor in the S is on a par with the pro, so if its for pure speed i would probably go with the black drives.

jennifer may be able to add more?

In the S, it’s a small difference, may or may not be noticeable.

Thanks for the replies - that’s good to know. For what it’s worth, I tested a full HD video clip in ProRes HQ and it opened very fast and played back without a problem, so read times seem fine so far…

“Full HD” is a bit meaningless - its bitrate which is important, and you can get some quite heavily encoded “full HD” clips which are lower bitrate than SD DVD-MPEG2.

The highest bitrate most consumer are likely to encounter would be blu-ray media, which is never more than 6 megabytes/second and tends to hover more around the 4MB/sec region, which even a regular drobo can easily maintain, let alone an “S”

when you say “for video” you don’t make it clear whether you are some kind of video professional and will be editing possibly uncompressed or very marginally compressed videos (in which case a RAID-0 array as a working/scratch disk would be far more appropriate for you). or if you are just a consumer wanting to play back lots of video

if its just for playback, any drobo, with the cheapest drives you can get, will handle the job easily.

Sorry for the confusion - I had simply meant ‘full HD’ as a kind of shorthand for the resolution - 1080p (1920 x 1080 progressive) which seems to be commonly understood as ‘full HD’ (disregarding the higher resolution formats 2k, 4k, and so on).

Likewise, I mentioned the codec as ProRes HQ - to signify the other aspect of the load. The video is compressed but has a high bitrate (around 220 Mbit/s - approx 27.5 megabytes per/sec) and retains a lot of colour information etc. It can be taxing for playback so was a simple one to check performance against.

I do work with video and usually in this codec or similar ones. Although I hadn’t initially thought the Drobo would be the primary scratch disk (I got it mostly for backup and centralised storage) I’m definitely interested in testing it for editing. I don’t work with uncompressed HD (or SD for that matter) so it could be fine, judging by this initial test.

RAID-0 would be nice but not necessary for me at the moment.

Thanks again for the input

I think you’d be OK for a single stream from the Drobo S, but pulling multiple streams will likely become problematic.

As a scratch/render disk, it’ll likely be good, and barring a throughput bottleneck, there’s usually a speed advantage having different source and output volumes.

thanks - that sounds right to me too - I’ll try to test it out and re-post in case anyone else is interested…

Just installed an eSata card (the Sonnet Tempo E2P) - in a 2008 8 core Mac Pro 2.8ghz with 8gb ram and am now getting about 60-70mb/second copying from an internal Seagate ES2 drive)…(nb. not a very scientific method - just manually timing how long a Gig takes and calculating the time, for a few times)…

I thought the main issue is the delay from the drive’s internal error correction feature and how cheaper ‘green’ drives lack a time limit on how long the drives takes to correct the error, thus making the RAID system think the whole drive has failed.
http://en.wikipedia.org/wiki/TLER

WD calls their time-limit feature TLER and other makers will use their own terms. It seems greedy that the inclusion of this little time-limit code in the harddrive firmware is an excuse for pricier ‘raid’ versions of the same harddrive.

I don’t know the exact logic of how Drobo handles unresponsive disks but it seems like a workaround for drives without TLER is to have the RAID system wait a little longer before concluding an unresponsive drive as dead.
http://www.tomshardware.com/forum/251076-32-raid-issues-western-digital-hard-disk

I think another issue is that a green drive may frequently spin-down and thus take longer to spin back up. If that delay is too long, the RAID system may see the drive as unresponsive and mark it as dead. Since DR sells Drobos with these WD Green drives, it’s possible their firmware has been tuned to deal with the quirks of green drives.

yeah - but that is only relevant if/when the drive encounters an error - which is pretty rare - so i’m not sure how that is relevant here?

Did a small test with some 1920x1080 ProRes 422 (HQ) files now that I have an eSata card and thought it might be useful to add.

I opened 3 at once in QuickTime, set their presentation size to half (just to see them all running at once) and had the Info overlay running too to see the playing FPS.

All 3 played back without a hitch and 4 played fine for about 2 mins before a choke (it’s unclear to me whether this is to do with throughput or simply the limits of the processing).

The combined bitrate of the 3 files was only about 390 Mbits (48.75 MB) due to the nature of the footage being quite sparse and I think more complex footage could yield a different result.

I realise again this is a subjective method and not necessarily indicative of either maximum or minimum performance while editing but I thought it would be useful to see what happened in a real world context.