Raid 1 vs Raid 5 for Small Office

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marley1

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What do you guys recommend for a small office that is doing just file sharing and a small sql database? this is for a dental client - a SQL Practice Management and a SQL imaging program.

I like Raid 5 for most cases but I figured Raid 1 would be faster. It would be a 4 drive raid 5 or a 2 drive raid 1 with a hotspare. Using SATA as well.
 
the raid5 with 4 drives will be faster than raid1 in every scenario.

EDIT: are you planning to put the OS on a separate drive? I hope you are not planning to partition the raid for both OS and DATA.
 
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I have a 4 drive SATA RAID 6 at my father's medical practice. Its more than fast enough and gives them the opportunity for two drives to fail.
 
I usually split he Raid 5 into 2 partitions, never heard that was a bad thing or not. OS would be on same array. Small office, bigger ones I step up the server and do raid 1 and raid 5
 
it's not best practice, and i know that is a buzzword these days but the only time it is really acceptable to partition a disk/array is for desktop/personal use.

when i say partition it is assumed that each partition will have a different use. in this case a wildly different use: OS and the DATA store.

i don't have a good analogy to give but basically consider wear and tear. and since you are using SATA you should separate i/o for OS and DATA access, especially when multiple access is happening.

if this is a small 4-8 user scenario then i wouldn't sweat it. go raid5/6 though for sure, whichever your budget can handle - meaning you might need a new card for raid6.
 
RAID5 is not the right choice for databases that are write-heavy (i.e. properly setup databases that cache the active part of the database and only updates/writes will hit the disk or RAID array; 10/90% read/write ratio. In that case, A 4-disk RAID5 is likely slower than a single disk.
 
RAID 5 can be pretty slow in writing.

RAID 1 can be very fast for multiple user access if you have a controller that supports split seeking.

Personally I would go with multiple RAID 1 arrays, reasons being: simplicity, quick rebuilds in case of failure, fast performance under heavy random workloads.
 
staticlag said:
Personally I would go with... RAID 1
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I agree, but possibly for different reasons:

Unless my customer needs more capacity than is available in a single drive (2TB currently), i always pick RAID-1. For myself and my customers, easy recovery completely outweighs the speed benefits of a large multi-spindle array. (Small businesses are notorious for failing to do backups, unless you are the one doing them, as part of a service contract)

I've worked on too many 5+ year old servers with a failing RAID adapter, flaky cables, or multiple "iffy" drives after fans have died and let the server cook. Its often tough to find a suitable replacement card to get a RAID array back up. With RAID-1, if the RAID controller fails, pull one of the drives, clone it to a SATA drive, connect it to an on-board SATA port, and you're back up and running, at least temporarily.

RAID-1 = simple. RAID-5/6 = complicated. Don't get me wrong, my home server has multiple RAID-5 arrays. But, for most small businesses, RAID-1 gives them all the speed they need, and is much easier to recover from a major failure. (Get a quote on data recovery for a RAID-5 from DriveSavers, DiskDoctors, etc. $5k+)

Awol
 
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staticlag said:
RAID 5 can be pretty slow in writing.

RAID 1 can be very fast for multiple user access if you have a controller that supports split seeking.

Personally I would go with multiple RAID 1 arrays, reasons being: simplicity, quick rebuilds in case of failure, fast performance under heavy random workloads.
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With any controller and drives produced in the last 3 or 4 years, RAID 5 is going to be faster than RAID 1 for 99.9% of workloads.
 
If you're concerned about performance, go with RAID10. If you want more storage space, go with RAID5.
 
inotocracy said:
If you're concerned about performance, go with RAID10. If you want more storage space, go with RAID5.
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that's such a blanket statement it's just crazy. you must know your application before assuming anything.

raid5 = fast read
raid10 = fast write

the difference however in write speed is a much smaller percentage gain than that of raid5 in comparison to the gains in reads you receive wtih raid5 over raid10.

that is to say if your database is going to be read only with 4+ disks raid5 is the light. however, if it is going to be write intensive then consider raid10.

Here is a bit of benchmarking to look at:
whidlj.gif
 
that's such a blanket statement it's just crazy. you must know your application before assuming anything.
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Agreed.

RAID 5 is fast at reads (approaches raid 0 speed for n-1 disks) but suffers poor write performance on random or small writes if it either the raid does not have a cache or the cache is not effective. The problem with writes that are smaller than the block size is that if the block is not in cache the entire block needs to be read first then updated then sent back to the cache to be written back at a later time or the data goes directly to the drives. In good controllers this write can be delayed or the block will at least stay in cache so that in the near future if the same block is needed the system does not need to read it from the array first. On crappy controllers or ones with no or disabled cache or windows software raid the read step generally always happens crippling performance.
 
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RAID 10 should do much better in random read/write compared to RAID 5 though.

So yeah, people should avoid blanket statements on RAID levels as there are too many variables at play including the tolerance level itself.
 
I've always done Raid 5 or Raid 1 noone of hte other levels, Raid 5 seems fine for a small office no?
 
I manage a 7 location dental client,

The location servers are RAID 1, used for practice mgmt databases, document redirection and shares.

The PDC is a RAID 5 server which does DFS replication from all the branch locations. Works great in RAID 1 at the branch's,
 
What PM software? Are they doing digital and what software? DFS is syncing what just files??
 
Dentrix practice managment, also doing digital xrays.

DFS is replicating the Dentrix Databases, users my docs and digital images (and at some offices, the old PM data) The data is then backed up again and sent offsite to two datacenters.

You have to be careful with some PM software, for instance, Dentrix uses C-Tree database which can be a pain.
 
That's interesting how fast does it replicate? Are the office running at same time??
 
I run
My Docs replication from 6 PM to 5 AM
Dentrix Replication from 11 PM to 5 AM
Digital Imaging from 6 PM to 5 AM

This is the same for all offices. Branch offices have T1's, main office has 2 bonded T1's that terminate into PRI for the phone system.

The initial replication took a few hours and weighed in around 5 GB's then the daily replications are pretty quick
 
And the office are functional at same times?

It merges the databases and images?

So if location a Sees a new patient x and add some bitwing xray, the next day at location b that patient x and xray will be in dentrix?

Any setup needed in dentrix or dfs does it all??
 
No, it doesn't merge any data, each office has its own DFS volume. Each office operates its own PM database, then it transfers to the home office at night for backup.

The central office can remote in to the branch offices to do scheduling and billing if they need. The VOIP system is setup with the appropriate call queues.


Dentrix has nothing to do with DFS that is all windows
 
marley1 said:
I've always done Raid 5 or Raid 1 noone of hte other levels, Raid 5 seems fine for a small office no?
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Let's put it this way. All I use at the office is RAID 6. I have 3 Hyper-V servers. Two of the servers use 8 7200rpm SATA drives (3ware 9650se and Adaptec 5805 controllers), the other has 8 5400rpm 2tb drives (LSI 1078 based controller). We serve files and Exchange email to 400 users, including many lab users who work on large images. We also have a VM for our recording software for student lectures. We have a web server VM. We have some SQL databases. The users are very happy with the speed and any slowdowns are due to our network design (old switches)- upgrade in process.

Unless your database is really poorly coded and/or you have thousands of processes/users accessing the DB, RAID 5 or 6 is fine. And let's face it, if you're in that boat, you should be getting a SAN and forget DAS all together.
 
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