Build your own HD storage, we did!
by Stephen PorthouseTen80 provide consultancy in building HD storage solutions around FCP based editing suites. Email Stephen Porthouse with enquiries.
Research
We looked long and hard at everything on the market in terms of HD storage, but in the end we decided to build our own solution.
This solution would take the form of a disk array of sorts, most likely a number of striped disks (RAID 0 all disks working concurrently to share load as data is divided between them). This type of array offers the greatest potential for speed and capacity, yet offers no redundancy if one of the drives fails. As we use FCP HD this would also be a Mac based array linking to a dual 2.5Ghz PowerMac G5.
The main criteria for the array were speed, capacity and affordability. With 4:2:2 1080i60 10bit requiring 148.3 MB/sec and uncompressed 4:4:4 1080p needing 222.4MB/sec (both plus 20% overhead), we were hoping our array would achieve in the region of 300MB/sec read and write speeds. Doing the maths, to capture a couple of hours of uncompressed HD would then require roughly a capacity of 1.5TB. We set the budget in the region of £2000 for drives, cabling, enclosure and controller card.
The emerging use of the SATA hard disk as a viable basis of high capacity video storage led us to research this against the more established SCSI solutions. While 15,000rpm U320 (320MB/sec) SCSI drives were available and would certainly have proved fast enough, their maximum capacity at the time of research was 72GB. This, allied to costs of approximately £250 per drive, effectively ruled out a SCSI solution following our criteria above. By comparison a 300GB 7200rpm SATA (150MB/sec) drive could be purchased for approximately £100. Although with a theoretically slower interface, the cost and capacity of SATA would allow us to use more drives than SCSI would within our budget and also to gain a much larger array.
Once the decision was made to go down the SATA route it was then a question of deciding on the correct components to marry together. These were as follows –
SATA Controller Card
To provide enough bandwidth and potential capacity we were hoping to use an 8 channel card which initially led us to the Rocket Raid 1820A card by HighPoint. However we started to hear of various problems other users were having, which kept us searching. At this time the Sonnet Tempo-X SATA 4x4 card appeared on the market and seemed by all accounts to be a reliable bit of kit particularly as its drivers were native with OS X. As its name suggests the Tempo-X also supports PCI-X slots (these run at a maximum of 133Mhz as opposed to 33Mhz with standard PCI) and has 4 external connectors and 4 internal connectors.
Hard Disks We started by looking at 300GB Maxtor Maxline III drives as they were touted as the fastest SATA drives available, but as these drives were seemingly impossible to source in the UK, and as we heard of performance related issues with these drives when utilising the Tempo-X card, we decided to go for the slightly slower drive with better reliability. As building large SATA arrays is pretty cutting edge stuff there was very little information regarding the performance of other potential drives. In the end we made a decision based on specs and manufacturer reputation and opted for 9 x 300GB Seagate Barracuda 7200.8 drives (8 drives in the array plus one spare).
Enclosure
We required an enclosure with enough bays, power, and cooling for our 8 drive array which initially seemed like a difficult prospect. Enterprise grade enclosures with redundant PSUs and hot-swappable bays are quite freely available but at a cost and normally for use within racks whereas we were looking for a more “desktop” type solution and had no real need for enterprise features - at least not at this stage. Our options seemed to be either importing an enclosure from the US or modifying a SCSI HD tower, neither of which was ideal. However during a visit to a computer fair in London a supplier of the perfect solution was found, i.e. a bare enclosure with enough bays, power, and hopefully cooling in a form factor not dissimilar to a PowerMac G5.
Building
As the array was to be built in London and then shipped to our Paris studio on a set date, we faced the usual deadline of sourcing parts and found particularly that getting hold of SATA cables at short notice is easier said than done! However, with all the necessary parts acquired the actual build was relatively straightforward.
To begin with we had to screw a spacer to either side of each drive to convert their 3.5 width to the enclosure's standard bay width of 5.25”. As we mounted each drive into the enclosure, we noted its serial number and position to make easier identification of problematic drives later on. For an aesthetic flourish we also mounted a couple of UV lights into the inner front of the enclosure, as the array was just asking to glow UV in the dark!
With each drive connected to a power and SATA cable we were able to install the cover onto the enclosure and then install the Tempo-X card into the Mac. To achieve maximum throughput the card needs to be in the 4th PCI slot. As the card has 4 internal connections we had to remove a spare PCI blanking plate and pass 4 cables into the Mac through this hole. Not an ideal way of doing things and we are hoping to source a blanking plate containing 4 SATA connectors which will tidy this up. At the time of writing however Sonnet have introduced the Tempo-X eSATA 8 card which has 8 external connectors and would be the better solution for an external array of 8 disks.
Testing
Not without some trepidation we powered up the array for the first time and then, after a 30 second wait, the Mac itself. Sonnet recommends this procedure to prevent drives failing to boot up. On opening Disk Utility we found all drives were present and correct. We then formatted the drives into a striped array and set about doing some basic copying from the Finder as an initial check. All seemed more than fine so far. We then launched the Blackmagic Disc Speed Test utility which ships with the card and tests the initial speed of your array. Read and write speeds of 450 and 460MB/sec respectively were reported which was far more than we had hoped for, and the formatted capacity of the array is 2.2TB.
We used Temperature Monitor to check the drives were running within their 60 degree maximum and found that even after a day's continuous use the drives remained steady between the high 30s and low 40s degrees. Should further cooling be required this will be possible given the enclosure's inner space and power capacity.
Surprisingly, the noise from the enclosure is not intrusive. Neither the enclosure's fans nor the drives are particularly loud and the hum from the array doesn't significantly add to our studio's room tone.
Things Still To Do
SATA Interconnects
To tidy both the back of the Mac and array, and to remove the direct connections to both Sonnet card and hard disks, we will be installing some SATA interconnects once a suitable source is found for them.
Raid software
We intend to purchase a copy of SoftRAID and do some comparison tests between this and Apple Disk Utility.
Testing
We will be further testing the speed of the array over its whole capacity to gauge the speed 'drop off' as the disk fills up. We will also continue the drive temperature tests to gauge the need for any extra cooling.
Ten80 provide consultancy in building HD storage solutions around FCP based editing suites. Email Stephen Porthouse with enquiries.