pendragoncrw

Raid 1 On A Budget

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Hi all,

I need to use raid1 on a Win2k3 server. The server specs are: P4 3.0ghz HT cpu, 1gb RAM, and two hitachi 120gb pata drives w/ 8mb buffer. I intend to mirror the 120gb drives. I've used the Win2k built-in Raid1 with no ill effects and the performance was acceptable. I've noticed a propensity of controllers like this one on eBay and am wondering if they would offer better performance than the win2k software raid1. I'm not sure I want to spend the $ for one of the newer 3ware raid controllers.

Any and all suggestions welcome.

Many thanks,

Chris

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The 3ware 5800 is ancient, (first generation, now on fourth) and IIRC is an ATA-33 card. 3ware has the complete manual online which has details on drive sizes supported, etc. The latest drivers are 4 years old.

If you're just mirroring two drives, stick with the software RAID. It's fast and simple.

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i agree, RAID 0 and 1 are simple. little system drag. and with 2 disks you're likely to get great performance.

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Would you recommend putting both drives on the same channel or one on the primary and one on the secondary. After setup is done I'll likely pull the optical drive out since I won't use it very much.

Thanks again,

Chris

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Would you recommend putting both drives on the same channel or one on the primary and one on the secondary.  After setup is done I'll likely pull the optical drive out since I won't use it very much. 

Thanks again,

Chris

One drive per controller, else performance will suffer.

Thank you for your time,

Frank Russo

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Would you recommend putting both drives on the same channel or one on the primary and one on the secondary.  After setup is done I'll likely pull the optical drive out since I won't use it very much. 

Thanks again,

Chris

One drive per controller, else performance will suffer.

Thank you for your time,

Frank Russo

One drive per channel. I assume that's what the previous poster meant.

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>I think so too, otherwise those 12-channel controllers would be a waste.

If you put both drives of a mirrored set on the same channel, the R/W operations would have to be sequential, cutting down performance.

One channel, one I/O operation at a time.

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This begs the question: If one of the drives fail, does the computer freeze? And when it comes time to rebuild, what is the procedure?

p.s. how easy is it vs. hardware solutions for cheap?

Depends. Usually it just errors out and the drive goes offline, but like anything, if certain hardware failures occur then the system locks up. I've seen this happen with Software RAID, Adaptec RAID and 3Ware RAID. YMMV.

If you're rebuilding with a new drive you need to do it manually through the built-in Windows Disk Management. If you just need to remirror, that is done automatically. It's very, very, very simple.

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This array is replacing a 60gb win2k software raid1 array that died over the weekend. I was running 3 drives in my server.

1. System drive-gets ghosted after a software change (not very often)

2. Data Drive1-Raid1 disk1

3. Data Drive2-Raid1 disk2.

If the system drive dies, I slap another one and restore the ghost image. If the one of the raid1 drives dies, I break the mirror, backup the data, put in a new drive, and then re-mirror. So far, no problems in the event of failures.

Chris

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i agree, RAID 0 and 1 are simple. little system drag. and with 2 disks you're likely to get great performance.

RAID doesn't always mean better performance, for RAID 1 write time would all but double, but read times will be slightly better. Main advantage of RAID 1 is data redundancy not performance. RAID 0 would provide better performance but doubles the risk of data loss if 1 HDD fails all data will be lost.

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write speed is usually not affected much by RAID 1. It is hurt, but only slightly.

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RAID doesn't always mean better performance, for RAID 1 write time would all but double, but read times will be slightly better. Main advantage of RAID 1 is data redundancy not performance. RAID 0 would provide better performance but doubles the risk of data loss if 1 HDD fails all data will be lost.

I think you need a primer on RAID.

RAID 1 writing is about the same as non-raid since writes happen simulanteously. In general, reading is about the same as RAID 0, which is twice as fast as a single drive.

As always there are exceptions (like two drives on a single PATA channel) or a stoopid RAID controller.

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RAID doesn't always mean better performance, for RAID 1 write time would all but double, but read times will be slightly better. Main advantage of RAID 1 is data redundancy not performance. RAID 0 would provide better performance but doubles the risk of data loss if 1 HDD fails all data will be lost.

I think you need a primer on RAID.

RAID 1 writing is about the same as non-raid since writes happen simulanteously. In general, reading is about the same as RAID 0, which is twice as fast as a single drive.

As always there are exceptions (like two drives on a single PATA channel) or a stoopid RAID controller.

Disagree, I think its you that needs the primer. Software RAID is no way comparable to hardware RAID performance otherwise everyone who buys a hardware RAID controller is wasting their money. And the write time for RAID 1 is longer compared to a single drive. And read performance although better than a single drive is no way 2x the performance of each individual drive due to overheads.

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Software RAID is no way comparable to hardware RAID performance otherwise everyone who buys a hardware RAID controller is wasting their money.

And the write time for RAID 1 is longer compared to a single drive. And read performance although better than a single drive is no way 2x the performance of each individual drive due to overheads.

That's very weak reasoning.

Why are (much) writes slower?

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Varous system factors will mean less than a linear increase (less than the following ideal).

As compared to single drive

2 Disk RAID1 (single controler) gives potentially

* double read speed

* same or slighly slower average random access under benchmarks, still more read IO's per second.

* same write speed

* data mirror to protect single hard disk failure. Same risk of software errors causing problems and other system failures.

2 Disk RAID0 (single controler) gives potentially

* double read speed

* double write speed

* same or slighly slower average random access under benchmarks, still more IO's per second.

* double write speed

* no data redundancy and double risk of falure.

Not all hard drives are designed (firmware) to be safe/fast under RAID0 or RAID 1.

...

RAID1 doubles the amount of data that has to be transferred for writes.

Software RAID1 can limit performance due to wastage of the system to controller bandwidth. Modern Intel/Microsoft software RAID1 is faster then a >2yr old hardware ATA RAID solution.

RAID0 shares IO's between disks.

Go hardware RAID for servers/workstations with plenty of disks and plenty of high PCI bandwidth.

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>If the one of the raid1 drives dies, I break the mirror, backup the data, put in a new drive, and then re-mirror.

Check to see if your RAID ctlr has the option to add a standby drive, it sits on an unused port on one of the channels and you'll be able to rebuild on the spot, without even shutting off the power.

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I'm using Win2k Server software raid which does not have the hot-spare capability. A few hours downtime is not a big deal to me so that's not really a deal-breaker feature. A couple of systems I've worked on with 3ware controllers did have hot-spare and that was a great feature in evironments that needed every last minute of uptime.

Chris

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I'm not quite sure I understand your question. Is that "few hours" in the "how could anybody take this long", "how can you afford the downtime", or "that's pretty speedy"? :D

This is a storage server for my home (iso images, pictures, mp3's, documents etc. for 4 people). When it used to be a 30gig raid1 array and one of the 30's died, it took about 1hr to do the swapping and the rebuild. I usually include 1hr or so of extra time anytime I estimate anything to compensate for the unpredictable.

Chris

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