7 ms·

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

by NovaS1X 11y ago

ymse 11y ago
It takes 8 hours 20 minutes to write 15TB over 500MBps. Why would you want to stick one of these in a RAID though? ..it would be more like Redundant Array of Prohibitively Expensive Drives. (I'll show myself out)
- rgbrenner 11y ago
  article says 1200MBps.. so more like 3.5 hours.
  - ChoGGi 11y ago
    I wonder how that 1200MBps will hold up with the thermal throttling with their other V-NAND products (SM951/950 Pro), especially when doing a raid rebuild? I happen to have a 950 Pro, and normal usage keeps the temperature at reasonable levels (though I stuck heatsinks on mine), but this is much more dense (512 vs 2 on the 950 Pro).
    - kabdib 11y ago
      FusionIO drives (PCIe attached flash storage) have serious heat sinks. The heat sinks are not for show. I get about 2GByte/second sustained. It's fun :)
      - baq 11y ago
        i remember the times when RAM of this speed was something to brag about... guess i'm getting old.
- software_radio 11y ago
  #TRIGGERED
- rbanffy 11y ago
  RAPD is a catchy acronym.
  - theandrewbailey 11y ago
    You mean RAPED?
jo909 11y ago
> 15.36TB > sequential read and write speeds of up to 1200MBps ~4 hours to read/write a whole drive ain't too bad. Of course there might be other bottlenecks in your raid, or you only reserve so much speed for rebuild, but the drives size is not the problem.
- astrodust 11y ago
  I'm kind of shocked that this drive is so slow. That's an impressive benchmark compared to your run of the mill consumer drives, but the new PCI-e drives Apple has been shipping are already beyond 2000Mbps. http://blog.macsales.com/30725-owc-tests-speed-of-ssd-in-2015-15-macbook-pro-with-retina-display http://blog.macsales.com/30725-owc-tests-speed-of-ssd-in-201... I would've expected Samsung to be able to best that. They make the chips, after all.
cm2187 11y ago
I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?
- zanny 11y ago
  A Raid 5 could work, since you are not writing the same data. You would need a hardware coprocessor to handle generating the checksums at 4GB/s though.
  - pixl97 11y ago
    >You would need a hardware coprocessor to handle generating the checksums at 4GB/s though. A first gen i5 2.4GHz can generate XOR for RAID5 at 4GB/s. Newer generations at faster core speeds should be able to beat that significantly. ... I went and tested this on a Intel(R) Xeon(R) CPU E3-1220 v3 @ 3.10GHz [1053854.445872] avx : 17860.000 MB/sec [1053854.475878] raid6: sse2x1 gen() 6554 MB/s [1053854.492857] raid6: sse2x2 gen() 9070 MB/s [1053854.509853] raid6: sse2x4 gen() 11273 MB/s [1053854.526848] raid6: avx2x1 gen() 21554 MB/s [1053854.543844] raid6: avx2x2 gen() 25152 MB/s [1053854.560838] raid6: avx2x4 gen() 29167 MB/s [1053854.560839] raid6: using algorithm avx2x4 gen() (29167 MB/s) [1053854.560840] raid6: using avx2x2 recovery algorithm
  - ryao 11y ago
    RAID 5 is terrible with 4K random IO. I know guys who measured >1 million IOPS with MD RAID 0 and then switched to MD RAID 5 only to have performance drop from read-modify-write overhead. They could not believe that RAID 5 was the cause.
- chipperyman573 11y ago
  Yeah, the statistical chance of the same thing happening on both drives is the same, but the chance of it happening at the same time is pretty low.
  - 11y ago
antongribok 11y ago
If you use a fully distributed storage system, like Ceph (or 3Par?), then rebuild times during a drive failure would be significantly lower. Also, any self-respecting storage system (RAID or not) will lower rebuild priority over normal IO. To give a specific example, let's say you have a 10-node Ceph cluster with 10 of these SSDs in each node filled up to 75% capacity. During a rebuild you throttle down to 50 MBps per SSD. After a single drive failure, the remaining 99 SSDs will work together to redistribute the data in about 40 minutes: $ python3 -c "print(round((15.36 * 1024 * 1024 *.75) / (50.0 * 99) / 60.0, 2))" 40.67 The 50 MBps per drive may seem like a low number, but that actually means each node has to move data at roughly 5 Gbps over the cluster network. * Edited to fix the python line where the multiplication characters converted to italics formatting.
- beagle3 11y ago
  Isn't 50MBps closer to 0.5Gbps than 5Gbps? Where does the other factor of ten come from?

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

by NovaS1X 11y ago

Impressive. First question that pops into mind is how long the rebuild time would take if one of these failed in a RAID. I can imagine it'll take a while.

ymse 11y ago

It takes 8 hours 20 minutes to write 15TB over 500MBps. Why would you want to stick one of these in a RAID though? ..it would be more like Redundant Array of Prohibitively Expensive Drives. (I'll show myself out)

rgbrenner 11y ago
article says 1200MBps.. so more like 3.5 hours.
- ChoGGi 11y ago
  I wonder how that 1200MBps will hold up with the thermal throttling with their other V-NAND products (SM951/950 Pro), especially when doing a raid rebuild? I happen to have a 950 Pro, and normal usage keeps the temperature at reasonable levels (though I stuck heatsinks on mine), but this is much more dense (512 vs 2 on the 950 Pro).
  - kabdib 11y ago
    FusionIO drives (PCIe attached flash storage) have serious heat sinks. The heat sinks are not for show. I get about 2GByte/second sustained. It's fun :)
    - baq 11y ago
      i remember the times when RAM of this speed was something to brag about... guess i'm getting old.
software_radio 11y ago
#TRIGGERED
rbanffy 11y ago
RAPD is a catchy acronym.
- theandrewbailey 11y ago
  You mean RAPED?

jo909 11y ago

> 15.36TB > sequential read and write speeds of up to 1200MBps ~4 hours to read/write a whole drive ain't too bad. Of course there might be other bottlenecks in your raid, or you only reserve so much speed for rebuild, but the drives size is not the problem.

astrodust 11y ago
I'm kind of shocked that this drive is so slow. That's an impressive benchmark compared to your run of the mill consumer drives, but the new PCI-e drives Apple has been shipping are already beyond 2000Mbps. http://blog.macsales.com/30725-owc-tests-speed-of-ssd-in-2015-15-macbook-pro-with-retina-display http://blog.macsales.com/30725-owc-tests-speed-of-ssd-in-201... I would've expected Samsung to be able to best that. They make the chips, after all.

cm2187 11y ago

I thought RAID and SSD were a terrible combination. As if both drives do exactly the same writes at the same time, chances are they will fail at the same time. Plus most RAID controllers don't support TRIM. Has the thinking changed?

zanny 11y ago
A Raid 5 could work, since you are not writing the same data. You would need a hardware coprocessor to handle generating the checksums at 4GB/s though.
- pixl97 11y ago
  >You would need a hardware coprocessor to handle generating the checksums at 4GB/s though. A first gen i5 2.4GHz can generate XOR for RAID5 at 4GB/s. Newer generations at faster core speeds should be able to beat that significantly. ... I went and tested this on a Intel(R) Xeon(R) CPU E3-1220 v3 @ 3.10GHz [1053854.445872] avx : 17860.000 MB/sec [1053854.475878] raid6: sse2x1 gen() 6554 MB/s [1053854.492857] raid6: sse2x2 gen() 9070 MB/s [1053854.509853] raid6: sse2x4 gen() 11273 MB/s [1053854.526848] raid6: avx2x1 gen() 21554 MB/s [1053854.543844] raid6: avx2x2 gen() 25152 MB/s [1053854.560838] raid6: avx2x4 gen() 29167 MB/s [1053854.560839] raid6: using algorithm avx2x4 gen() (29167 MB/s) [1053854.560840] raid6: using avx2x2 recovery algorithm
- ryao 11y ago
  RAID 5 is terrible with 4K random IO. I know guys who measured >1 million IOPS with MD RAID 0 and then switched to MD RAID 5 only to have performance drop from read-modify-write overhead. They could not believe that RAID 5 was the cause.
chipperyman573 11y ago
Yeah, the statistical chance of the same thing happening on both drives is the same, but the chance of it happening at the same time is pretty low.
- 11y ago

antongribok 11y ago

If you use a fully distributed storage system, like Ceph (or 3Par?), then rebuild times during a drive failure would be significantly lower. Also, any self-respecting storage system (RAID or not) will lower rebuild priority over normal IO. To give a specific example, let's say you have a 10-node Ceph cluster with 10 of these SSDs in each node filled up to 75% capacity. During a rebuild you throttle down to 50 MBps per SSD. After a single drive failure, the remaining 99 SSDs will work together to redistribute the data in about 40 minutes: $ python3 -c "print(round((15.36 * 1024 * 1024 *.75) / (50.0 * 99) / 60.0, 2))" 40.67 The 50 MBps per drive may seem like a low number, but that actually means each node has to move data at roughly 5 Gbps over the cluster network. * Edited to fix the python line where the multiplication characters converted to italics formatting.

beagle3 11y ago
Isn't 50MBps closer to 0.5Gbps than 5Gbps? Where does the other factor of ten come from?