Synology Launches Enterprise NAS Line

[rpwoodman]

I don't understand what business would buy a product that only has software raid - taking 8+ hours to rebuild an array if a disk dies; a cheap $1000 PC with hardware raid takes under one hour. To a busines, their data is their life.

Seems odd to me.

 

[beisser]

you show me one pc that is able to rebuild a raid consisting of 2 or 3 tb drives in less than an hour.

small calculation example.

since the array has to write the information to the fresh disk it would be limited by the performance of said fresh disk.

lets say you have a raid consisting of 3tb drives and you say it will get rebuilt in 1 hour by a sub $1000 pc, that would mean the fresh harddrive has to write a whopping 833,33 MB/sec to accomplish that. thats a little unrealistic i would say even if you had solid state drives.

if we use the more realistic sustained writespeed of 100 MB/sec, we arrive at 8,33 hours to fully resync a raid-array consiting of 3tb drives.

no hardware-raid-controller will make this any faster.

its a different story if you have raids consisting of many small sas/scsi-drives, but we are talking about el-cheapo sub $10000 hardware here...

 

[rpwoodman]

It was a 1Tb disk that was used, using RAID 1, and a Dell desktop.
I was sure it took 40 mins to recreate the array, but my memory must be playing tricks on me - certainly the numbers don't add up - using the figures below, it would take a little over 2 1/2 hours:

100MB per second
1000MB (1GB) in 10 seconds
1000GB in 10,000 seconds - 166minutes

(I'm aware that formatted capacity is somewhat less - this is just easier mental arithmatic)

My mistake - sorry.

Having said that, 2 1/2 hours is considerably better than 8 hours which I understood to be how long it takes to rebuild a raid array in a NAS such as the Synology (feel free to correct me if your experience is different), tho your calculations are that it would be able to recreate a raid array using 3TB disks in this time - when it's using software raid, would it really be able to have a constant throughput of 100MB/s? I'm not sure I know where the work happens, but it can't just be a matter of copying data around - there must be some processing to generate parity information for example?

 

[beisser]

i guess it all depends on what cpu is used in the nas. multicore atoms or better cpus should be able to squeeze those 100 mb out of the disks.

i have one nas using a singlecore atom (readynas ultra 4) and one nas using a pentium dualcore (readynas pro) and both are limited by the harddrives when resyncing the array.

your assumption is correct for slower nases though because the kirkwood or slower cpus cant calculate the needed information fast enough.

i also have a readynas nv+ with a low power sparc cpu and that needs a bit longer for the same resync.

fact is, the cpus used in the nases described in the article have more than enough horsepower to resync the array at whatever speed the harddrives are capable of without breaking a sweat.

 

[jramskov]

3 years limited warrenty? Not quite enough for business.

 

[rpwoodman]

3 years limited warrenty? Not quite enough for business.

I'm not sure about that. The company I work for (not a huge company) will write off assets over 3 years, that includes $200 SANs. It may well impact the decision making process of smaller companies tho.

rgds