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RAID5 vs RAID10 for VPS
Hello,
We are considering to switch from RAID5 to RAID10 on all our Xen nodes to provide more performance for our customers. We need a final feedback from the LET community.
Is it worth it?
RAID5 vs RAID10
- Is it worth it to switch our Xen nodes from RAID5 to RAID10?61 votes
- Yes86.89%
- No13.11%
Comments
Answer is: depends.
Old SATA desktop disks will have to be in raid 10 especially with software raid to deliver a minimum of performance, while SAS short stroke disks will do fine in raid 5, until a drive fails and then the remaining will crawl until the disk is replaced and raid rebuilt. Raid 6 shortens this period.
google it
I think RAID10 has replaced RAID5 in almost all uses now.
http://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html
Also, DO NOT use RAID5 on SSD (edit: unless the SSD is an enterprise grade drive)
RAID 10 will not only improve I/O performance in general but also ensure everything works smoothly during RAID rebuilds. So switching to RAID 10 will definitely improve performance of your nodes for your customers.
RAID 5 is dead.
Still I/O cycles limited and lifetime will be decreased due to checksumming.
Surely worths it, better performance and reduancy.
That is mostly just an urban legend, depending on the number of disks, raid 10 writes much more than raid 5 ever will. If the raid is hardware and which will do TRIMM, the parity will also be done in the controller too, so no overhead.
most of VPS will write to HDD, so use only RAID10 - it has no write penalty. I strongly suggest to use SSD instead of HDD, get few 1Tb Samsung 850 Pro, backup daily to 3Tb HDD in same server if its for VPS.
Yes ofcourse ! RAID10 is always a win over RAID5 when it comes to VPS provisioning & data handling.
we use large arrays 16x3Tb HDD for large virtual servers nodes and small nodes each with 2x1Tb SSD + 2x3Tb SATA HDD for backups + remote snapshots for SSD VPS.
really...
First, in average, reading happens 5 times more often than writing.
Second, RAID 10 has 2:1 write penalty as it has to duplicate the data. Only RAID 0 has no penalty in terms of IOPS.
yeah, raid 5 has a double penalty: 4:1, but modern controllers are mitigating this if you have caching and battery by queuing and coalescing iops for the same drive, but this is not possible to the same degree in raid 10 because the data must be written to 2 different drives. With a modern controller, the IOPS penalty difference is much reduced.
In short:
Old hardware, sw raid, go with raid 10 to make it remotely usable;
Good hardware, hardware raid with serious caching, go with raid 5, especially in SSDs, as the IOPS are not so important there, but the amount of data written does matter.
And where is this pairity stored ?
Why you have disk space (N*DS) - DS
Where N = number of drives and DS is size of drives ?
In addition to storing data you store parity, which means that you need MORE write cycles to store data + parity not less, and not the same, MORE. SSDs have limited write cycles? agreed? Than more write cycles = shortened lifespan of the drive.
I wasn't talking about the performance penalty. I was talking about much more important thing - lifespan penalty. That's why RAID 5 is dead.
I does not matter what you are talking about if you do not understand how RAID and SSD work. Stop relying on sensationalist articles written to promote products and learn the basics instead.
In the case of RAID5, if you do have a good controller, this will work towards GREATLY reducing the number of writing IOPS as it gets them in the same operation and fills the matrix which is written as best as it can. Theoretically you have more IOPS, but in reality, with a good controller, you have fewer writes, unlike in a raid 10 where the data must be duplicated.
In Raid10 you write data on 2 disks, same stuff, in raid5 you write a parity on another drive, say, you write 1 gb in a raid 10 with 4 drives, it will take 2 GB of actual cells written, while on a raid 5 with 4 disks, will take only 1.33 GB of actual cells written at the expense of twice the IOPS, but distributed on all the disks, and a bit of parity calculation, which is done in the controller anyway, therefore transparent to the OS.
With a good HW controller you have fewer real writes to the real cells taking advantage of the full matrix written anyway, AND you have less data written, therefore SSDs last MORE than in the case of RAID10. The only REAL risk, is the classical one, depending on the number of disks, you have more of a chance to lose 2 disks and therefore the data in raid 5 than in raid 10, where you can lose two disks (if you are not really unlucky to lose exactly the ones holding same data) and still have the data, but with modern controllers which monitor disks health, can have spares, etc, this risk is again reduced if you plan ahead.
RAID5 is dead for people relying on "popular science" over the internet, intended for the average joe and his gaming rig, not for the people which are professionals.
Capisci? If you did not, yet, I wont try to explain again, it is your loss.
Thanks to you all for your valuable inputs. Really much appreciated.
Raid 5 can be hard with low-end drives. With good (data-center enterprise-grade) hard drives and hardware RAID controller it can give better results compared to RAID 10 especially in lifespan. Just as @Maounique said - there should be less or same number of writes to disk while RAID 5 gives more space.
To the op:
If you are not professional, you should go with RAID 10 anyway though. Just easier to maintain and understand.
I would also recommend to avoid suggestions from "wtf-unknown" companies like @tgk76 . Hostkey is tiny hosting provider, less than summerhosts. So you would be better to ignore @tkg76, i'm basically find it bad, that it's still not muted out there (i am afraid that LET will become WHT there only shitty unadequate people advertise their services with signatures and messages are just blablabla). Hostkey have no knowledges on performance as well as highload for sure. My experience with them ends in one purchace, 100 iops on hard drive I/O, and then their refuse to refund.
@Profforg host key isn't small lmao.
As i said. Summerhosts are bigger.
They flood that they have enterprise clients, but there are no any proof.
Less than 1000 visitors per day on all their websites combined.
I know Russian market very well, because i live here. Hostkey is not even a player. They are just loosers which tries to sell shit to stupid people (like their anti-ddos for 300$ per 1 mbps of bandwidth).
If you have adequate proof to counter my point of view, please provide them.
I don't know many Russians using them either (most are on .masterhost and similar), though they host some foreign Warez sites - IPs are "Mir Telematiki" which i havent seen in use by much CIS/RU either.
They seem to have some scale though, with a few hundred servers.
This isn't something you decide by a poll, its something you decide based on gathered data . . . it's not going to help performance if disk I/O is not already a bottleneck.
Scary.
You will get best performance in RAID 10 comapre to RAID 5. Also I am suggesting you to use SSD.
Yeah, I did not vote, because the answer is, as in most cases: depends.
I just love the TL;DR generation which knows it all.
I did not said, that they have zero clients. Most probably they have some. All have right? Noobs never die because new generations born.
I agree, that some warez sites can be hosted on their NL locations, that's visible on their AS info. I also seen some people who ordered their anti-ddos in Russia (not affective and very bad price).
From their AS overview it's rather easy to understand, that their clients are total noobs who just got cheated by hostkey. I also don't see any big websites hosted by them, most are very little.
Doubt so, no proof.
Just do raid 0 only >.>
Prove it.
I think that @Maounique needs to learn the basics, rather than you.
Prove what? That you have no idea what you are talking about? I think you proved that by saying raid 5 writes more data than raid10.
Why not put it to the test - setup two boxes, run the same Bonnie++ or similar script on the disks and see the results.
an interesting analysis, relevant to this topic
http://www.dell.com/downloads/global/solutions/tradeoffs_RAID5_RAID10.pdf
Thank you all for your valuable inputs. We are moving to RAID10 by the end of this month for all new VPS orders. And old VPS instances on RAID5 shall be migrated to RAID10 host by customer request.