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Decisions decisions . . .
05-03-2013, 07:10 PM
Post: #11
RE: Decisions decisions . . .
I need to replace a busy xserve with three internal 2tb sata drives with the apple raid card, in a raid-5 array and an ssd boot drive (early 2009 - top of the line at the time).

it runs email (kerio connect), two parallels VM's running windows server with oracle databases, and a large fileserver - 2tb worth of active and historical files.

the company is a package design firm. some small files, some very large files. and lot of email. lots and lots of email!

I'm trying to judge if a Drobo 5D and a top of the line mac mini will be an adequate replacement. I know the streaming performance of the 5d with large files is very good, but i dread that the interactive performance of it with TONS of very small files may, well, suck.

I need a total of about 5TB of usable space. So i guess i need at least 2tb drives x 5, with dual-redundancy turned on. and of course an mSATA to speed it up.

How much of a difference is there between fast and slow hard drives in the 5d?

I have 2 months before i have to purchase this, so i'm hoping for the new Seagate SSHD to become available. Curious if they will boost performance of small file read-writes.

any advice would be much appreciated.
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05-03-2013, 09:49 PM
Post: #12
RE: Decisions decisions . . .
(05-03-2013 07:10 PM)dalenorman2005 Wrote:  I need to replace a busy xserve...it runs email (kerio connect), two parallels VM's running windows server with oracle databases, and a large fileserver - 2tb worth of active and historical files.

I'm trying to judge if a Drobo 5D and a top of the line mac mini will be an adequate replacement. I know the streaming performance of the 5d with large files is very good, but i dread that the interactive performance of it with TONS of very small files may, well, suck.

You nailed it in your last sentence. Mail servers have very particular storage requirements. Drobo is not suited for this use.

I'll be surprised if you find any external RAID box or NAS (within your budget) that will meet your requirements for performance, redundancy, and recoverability.

Quick story:
I participated in a mail server "bakeoff" several years ago. Part of our testing involved pushing the product to the limits of our requirements.
We tested speed and reliability in "normal" use.
We then pulled a drive to simulate failure and tested again.
We continued to impair the products until our final test had us start a re-index, cut power, restart the server, remove a drive, and insert a new drive into the array -- all while measuring messages delivered per second and how long it took to load a large mailbox.
Our final test actually eliminated the most appealing product because we discovered performance became unacceptable during RAID rebuild, and high load caused the rebuild to take far longer than the documented and previously observed recovery times.

You earn respect by how you live, not by what you demand.
-unknown
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05-03-2013, 10:40 PM
Post: #13
RE: Decisions decisions . . .
thanks RDO, appreciate the input. please don't take offense, but can you clarify if you have any hands-on experience with the 5d? I've noticed a lot of speculation on this forum about how various drobo devices will perform based on the performance of other drobo devices.

I have lots of drobo experience myself, so i know their limitations. But i have no 5d experience. i'm hoping that the marketing around the 5d is at least somewhat accurate - that they finally perform well under load.

although the current xserve has never actually had a drive failure, so i don't know how bad it would be while rebuilding, i will say that it performs good enough as-is. it's not a high performing raid by any means... SATA (not SAS), raid 5, with only 3 drives.

i know the past generations of drobo would crumble under the load, but i'm still curious if the 5d with an mSATA might be up for the task.
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05-05-2013, 09:23 AM
Post: #14
RE: Decisions decisions . . .
hi dale,
btw not sure if its useful but when searching on xserve i saw a couple of links that might be useful:
http://appleinsider.com/articles/11/06/2...http://appleinsider.com/articles/11/06/28/xserve_users_report_performance_issues_after_apples_mac_os_x_10_
and
http://appleinsider.com/articles/10/11/0...http://appleinsider.com/articles/10/11/09/why_apple_axed_xserve_and_how_it_can_reenter_the_se

when you say your server is "busy", do you have a way to see how busy it is?
eg number of concurrent connections, GB transfered per day, etc
some of that info might be useful for more predictions on the 5n?

(btw i have XP home SP2, a Drobo v1 with 2x 1TB/2x 1.5TB WD greens, & a bkp Drobo v2 with the same + a DroboShare: unused)
& a DroboS v2 with 3xWD15EADS &2x1TB in DDR mode on win7, & a drobo5D (all usb)
  • btw i did a sustained (write) operation for about 6 hours, and got 13.2MB / sec ...objection? "sustained" :)
    (16.7MB/s on a v2 & 47-96MB/s drobo-s)
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05-05-2013, 10:13 AM
Post: #15
RE: Decisions decisions . . .
(05-03-2013 09:49 PM)rdo Wrote:  I'll be surprised if you find any external RAID box or NAS (within your budget) that will meet your requirements for performance, redundancy, and recoverability.

ahhh, you know, i could just buy the xserve off of it's lease for a few hundred bucks. they sell on ebay for under $500. these things are no longer valuable. I find it hard to believe that it can vastly outperform most external $1000 arrays.

i KNOW that a prior generation drobo would be a very bad idea. i've used several gen 1, gen 2, drobo S, and i know that they are very poor in demanding environments. i know they take forever to deal with drive replacements.

I'm hoping for someone with a 5d who has used it in similar ways to what i'm proposing who can share some hands-on experience with it. I've seen the benchmarks that peg it at 200+ mbps, but i'm worried that they highlight the very high streaming performance only and mask the real world workloads of lots of small, random read-writes.
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05-05-2013, 10:58 AM
Post: #16
RE: Decisions decisions . . .
It's true that the newer generation of Drobos has much improved performance, and I have no personal experience with them.

Mail RFCs like http://www.ietf.org/rfc/rfc2821.txt specify that data is committed to storage before the SMTP server returns "250 OK". This is basically a forced sync to disk. A busy server will perform many such operations per second. On top of that, it will be performing frequent small reads.
I don't know specifically how Kerio handles mail storage, but many servers accept data into a delivery queue, which is then copied to a more permanent place. This means that those small frequent reads/writes are for temporary data, so there's no chance to cache it for future access. I believe that would negate Drobo's SSD data tiering.

Also, if you're running multiple virtual machines off of the Drobo, that will put further mixed I/O demands. Certainly the newer generation will handle that better than the old generation would, but I don't know if the total demand on the storage will be too much for Drobo to handle.

The reason why I mentioned "your requirements for performance, redundancy, and recoverability" is because I strongly doubt that Drobo will be able to meet all those requirements at the same time. In other words, even if it performs well enough under normal conditions, what if a drive fails? If performance is seriously impaired for 2 days during a rebuild, you might be effectively offline during that time.

Put simply, the performance characteristics of Drobo are quite different than those of a single disk, or a JBOD. It's not a straight "upgrade" from your old, cheaper disk subsystem.

If you test this idea with a Drobo, I would love to hear the results!

You earn respect by how you live, not by what you demand.
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05-05-2013, 02:25 PM
Post: #17
RE: Decisions decisions . . .
Thanks. I'll update this thread.
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05-06-2013, 04:12 PM
Post: #18
RE: Decisions decisions . . .
How about a 5D with a couple 2.5" SSD's with three other HDD's?

Seems to work great with the B1200i for pretty intense stuff as well as transferring several small files and database information.

The mSATA card on the 5D only speeds up access times for files that are accessed often so it doesn't offer quite the performance boost that the 2.5" SSD's will.
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05-06-2013, 04:54 PM
Post: #19
RE: Decisions decisions . . .
(05-06-2013 04:12 PM)Caleb Wrote:  How about a 5D with a couple 2.5" SSD's with three other HDD's?

Seems to work great with the B1200i for pretty intense stuff as well as transferring several small files and database information.

The mSATA card on the 5D only speeds up access times for files that are accessed often so it doesn't offer quite the performance boost that the 2.5" SSD's will.



Great idea, but is that a feature of the 5d? i don't think it is. it would be awesome if it were, but i really don't think it works that way. i think the only data tiering that occurs is to/from the mSata, no?
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05-07-2013, 08:19 AM (This post was last modified: 05-07-2013 12:56 PM by Sky.)
Post: #20
RE: Decisions decisions . . .
The 5D doesn't do the same kind of data-aware tiering that the B1200i does, as it doesn't have enough drive bays to create two separate data tiers. The 5D will not have the IOPS needed to run VMs, serve files and be a storage backend for a mail server and an SQL server. These are the types of tasks for which we recommend a B1200i with a transactional tier, which tops out around 2300 IOPS. Our KB article regarding IOPS can be found at https://support.drobo.com/app/answers/detail/a_id/639.

To determine how many IOPS the server is using, follow the instructions at http://blog.synology.com/blog/?p=1431. This will help you determine the type of equipment you would need to replace the Xserve.

Links without the periods (arg):
https://support.drobo.com/app/answers/detail/a_id/639
http://blog.synology.com/blog/?p=1431

Sky
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