April 11, 201214 yr What is the biggest bottleneck in obtaining higher read and write speeds to the array? Is it the plain fact that unraid isn't RAID (5 or 6)? Can there be done anything to increase speed, apart from adding a cache disk?
April 12, 201214 yr Faster disks will increase access speeds up to a limit of about 120MB/s for reads. Ethernet runs at 125MB/s. Writes will be much slower than reads unless cache drive is used.
April 12, 201214 yr Author Follow-up question: What are the fastest and most reliable disks at the moment? No SSDs please. Is there a lof of difference between 5400-5900, Green and 7200 rpm disks? What would you prefer as cache disk? Are there any unraid settings that can improve speed?
April 24, 201214 yr I'm just about to start a thread on this so I'll post you the link when it is up. If you want any real noticeable gain over ~25mb/sec then you will need a cache drive, IMO it is absolutely worth getting one if most of the data you write on a daily basis isn't "life threatening" to lose, if you only write important files to the server occasionally then you can always manually move them straight to the array. These files should be backed up elsewhere as well anyway :-) Considering the price of drives at the moment, no drive is really worth getting if you can avoid it but from a performance/$ perspective I would say that a 500gb single platter drive should yield some decent speeds. Anything larger could double as a warm spare but might hinder performance a little. Once you have a cache drive the next bottleneck is likely to be either the network or the speed of the source (more specifically, your computer's drive). Gigabit cards in both, gigabit switch and CAT6 network cable will definitely help if you find your speeds stuck at about 11MB/sec. Any cache drive you use though, even an old PATA drive would likely make a noticeable difference to your write I haven't done any testing but my guess would be that you read speeds are likely to be bottlenecked by either a; the network, or b; the write speed of your destination (your computers drive again). You should see over 50MB/sec writes regularly with any cache drive, gigabit LAN and a source computer running WinXP or later.
April 24, 201214 yr New Seagate drives are reported to sustain 150MB/s. These should saturater a gigabit link.
April 25, 201214 yr New Seagate drives are reported to sustain 150MB/s. These should saturater a gigabit link. Is that the single platter 1TB drives? We had those come in at work a while ago, very impressed Pitty about the prices still though, depending on where you live might be a little different though. In AU they're still expensive. Umart Online Seagate SATA3 1TB 7200RPM 64mb Cache Internet Price: $104.00 Retail Price: $114.00 Stock level: >10 (Plenty of Stock) Model #: ST1000DM003
April 25, 201214 yr In playing with the 3TB Seagates with the 1TB platters.. I find the sustained read and write to be VERY fast. the bad news.. I find the random access read/writes to be horribly slow on a full drive. they also take longer then my Hitachis to create parity (when I use them for parity drives).
April 25, 201214 yr If you want any real noticeable gain over ~25mb/sec then you will need a cache drive, IMO it is absolutely worth getting one if most of the data you write on a daily basis isn't "life threatening" to lose, if you only write important files to the server occasionally then you can always manually move them straight to the array. These files should be backed up elsewhere as well anyway :-) My new bench box I can write to the protected array at 70MB/sec, using 1TB WD Green drives.
April 25, 201214 yr Are those the new Seagate 1TB platter drive? No. WD = Western Digital. Green = 5400 RPM green drives.
April 25, 201214 yr My new bench box I can write to the protected array at 70MB/sec, using 1TB WD Green drives. Wow. Could you post a list of your setup? Curious to see the specs. I get about 70MB/Sec most of the time writing to my cache drive.
April 25, 201214 yr If you want any real noticeable gain over ~25mb/sec then you will need a cache drive, IMO it is absolutely worth getting one if most of the data you write on a daily basis isn't "life threatening" to lose, if you only write important files to the server occasionally then you can always manually move them straight to the array. These files should be backed up elsewhere as well anyway :-) My new bench box I can write to the protected array at 70MB/sec, using 1TB WD Green drives. I was about to call BS, then I realized it was you. I must see the specs of this server! Looks like I might have to build a new unRAID box.
April 25, 201214 yr I was about to call BS, then I realized it was you. Areca ARC-1880ix-16-4G (4GB caching controller) with aggressive read-ahead enabled. 2 WD 1TB Green 5400 in RAID0 for data. 2 WD 1TB Green 5400 in RAID0 for parity. LAN is dual Intel 1Gb NICS in RR bonding mode and an HP ProCurve switch.
April 26, 201214 yr I was about to call BS, then I realized it was you. Areca ARC-1880ix-16-4G (4GB caching controller) with aggressive read-ahead enabled. 2 WD 1TB Green 5400 in RAID0 for data. 2 WD 1TB Green 5400 in RAID0 for parity. LAN is dual Intel 1Gb NICS in RR bonding mode and an HP ProCurve switch. i have an extra 1680 w/ 2gb cache. i just assumed it would be a total waste in unraid.
April 26, 201214 yr I was about to call BS, then I realized it was you. Areca ARC-1880ix-16-4G (4GB caching controller) with aggressive read-ahead enabled. 2 WD 1TB Green 5400 in RAID0 for data. 2 WD 1TB Green 5400 in RAID0 for parity. LAN is dual Intel 1Gb NICS in RR bonding mode and an HP ProCurve switch. I would call that "cheating" As its not really UNRaid - just a Mirrored Stripe (Raid 10) array LOL (just looked up the price of a Areca ARC-1880ix-16-4G) - costs about as much as my entire setup :eek:
April 26, 201214 yr As its not really UNRaid - just a Mirrored Stripe (Raid 10) array No, it is really unRAID. I can add drives, (RAIDed and plain) and mix RAIDed drives and regular. unRAID manages the parity, and I can easily reconstruct the RAID0 set if removed, and the regular nonRAIDed drives can, of course, be read in the event of a catastrophic failure. Granted, the Areca firmware provides ways to do much of what unRAID does (spindown drives, on-line expansion, etc.) but unRAID still has some advantages, such as the ratio of data to parity space, and parity-protecting single spindles. A common issue with striped RAID is the ratio of data space to parity space. unRAID is best suited for write-once read-mostly data. If you need speed, then you need striped RAID. I have about 10TB of stuff I am actively working on that needs the max raw speed. I also have SQL data that also needs striped RAID speeds. But I have another 20TB that I need on-line, but don't need fast access to. I also sometimes have to image large drives that I was doing to the cache drive, but sizes of evidence drives are getting bigger and I was going to have to go to a HW RAID solution for cache at the very least. So hybrid unRAID/RAID0 means I can have the best of both, and not compromise.
April 28, 201214 yr I think I'm in love with bubbaQ I'm probably going to be looking into a fast imaging setup some time in the not-so-distant future so I'll definately keep the RAID/unRAID combo in mind. I new you could stripe/mirror drives and use them as a disk in unRAID but raid 10 is impressive On a semi-related-semi-hijack-thread type note, I'm currently using an old 150GB 10KRPM Raptor drive as my cache drive (WD1500ADFD-00NLR5) and am wondering if this would be slower than a newer single-platter drive (1TB). I was also tempted to stripe a couple of drives to use as a cache drive but not sure how much difference it will make. I'll have a bit of testing gear setup soon so might try a few combo's and see what works well.
April 28, 201214 yr The raptor should have a better seek time but the new drive should have higher sustained throughput.
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