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Forum Discussion
shingled magnetic recording (SMR) hard drive fiasco - inquiring on recommendations
It's been a while since I jumped on the forum but what brings me here is my NAS volume utilization is hovering around 65%. I believe it's good until 80% and then starts to bark at you about storage ...
SamirD wrote:In fact, I have no idea why nas units haven't started incorporating sas controllers as they could use the much more reliable sas drives. There are no 'consumer' sas drives--it's all enterprise.
The lack of a full set of SMART parameters for SAS is one big reason, I'm sure. While enterprises typically run the drives 24/7 and replace them at the end of the warranty period, regardless of current performance, typical NAS users don't. So full SMART is needed for proper life evaluation.
My main NAS is a converted RD5200, so suports SAS (though the drives in it are from my old destop RN512 and EDA500, so are SATA), and I have an external SAS chassis also connected to it that does contain SAS drives. I do run it 24/7, but still wish I had a better set of SMART parameters. The performance of the external SAS chassis is equal to the volumes in the main chassis, very unlike external via eSATA port multiplication, so that's another reason to like SAS. I just wish there wasn't the SMART trade-off.
I know the server guys I know can pull the smart info off sas drives. But because sas drives are typically connected to a raid controller, you can't access them directly like sata drives. Still, with as durable as these drives are, if they're in decent running condition and haven't been reading and writing constantly their entire lifetime, they're usually in terrific shape for the price.
Very cool that you have an expansion unit connected to your main nas. That's another flexibility of sas--tremendous drive volume. When it comes to real storage arrays, sas is always there. That's why it dumbfounds me why nas manufacturers haven't incorporated sas into their higher end products.
My SAS drives are not on a RAID controller. While they have some SMART data, it is far less than what is available for SATA. I use HDSentinel to monitor them, I don't rely on the NAS capability (which also isn't available in the GUI for the expansion chassis drives).
Netgear did go with a SAS controller for the ReadyData 5200, which is why my converted unit supports them. The RR4360 also supports them (how else would one control 60 drives?) as did the EDA2000 and EDA4000 expansion units (by necessity). The RN4200V2 supported SAS in 8 of the 12 bays, but Netgear never really advertised that. OS4.2.x may have limited that, I never used one without upgrading to OS6, where they are suipported. They could have easilly used the same hardware as an RD5200 (which already shares 90% with it) and make it support SAS in all bays, but chose not to, likely so as to limit competition with their own ReadyData line. The ReadyData line has been discontinued, likely due to lack of sales, so that may be a factor in making any decisions.
Looking inside an RR2312, it looks like it's SAS. But I tried a SAS drive and it didn't work. It may be a BIOS limitation rather than the controller. I don't recall what lspci told me about the controller(s).
Since sas requires hardware support, if the drive doesn't fit, I bet it's not the right controller. I think os4 would support them fine since in dmesg you see the 'Fusion MPT SAS Host Driver' from LSI Logic being loaded.
SamirD wrote:Since sas requires hardware support, if the drive doesn't fit, I bet it's not the right controller. I think os4 would support them fine since in dmesg you see the 'Fusion MPT SAS Host Driver' from LSI Logic being loaded.
RR2312 drive connectors and cabling are identical to SAS, which is why I say it "looks like SAS": I installed a SAS drive, in one, but the OS didn't see it. But it may not have an actual SAS controller, the motherboard BIOS may not support them, or OS6 may even have something that blacklists them in that unit (though I doubt the latter).
OS 4 could stll blacklist SAS drives on a unit that needs the SAS controller to access SATA drives on it. Maybe not even intentionally, but AFAIK, the RN4200V2 was the only unit that shipped with OS4 that had SAS hardware, so they may simply have never implemented it.
I'm betting the backplane is sas, but it's attached to a sata controller as can be done, so that's why no sas support.
I think os4 clearly has sas support, but it needs the hardware. It would be interesting to take readynas os4 and install it on some non-netgear hardware with an sas controller.
Okay, so someone has tried it. :D
My Intel units will allow the software to boot on anything so an old lga775 Dell can be converted in to a nas easily supposedly. I haven't tried it myself yet.
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