What do you use?
Scott W
wegster at mindcore.net
Thu Jan 1 14:59:34 PST 2004
Scott Mitchell wrote:
>On Thu, Jan 01, 2004 at 01:09:23PM +0000, Francisco Reyes wrote:
>
>
>>On Thu, 1 Jan 2004, Scott Mitchell wrote:
>>
>>
>>
>>>As for RAID, we use Vinum, but only because I inherited a bunch of machines
>>>with hot-swap SCSI bays and no hardware RAID. It works well, once you have
>>>it set up, and I've even managed to swap out failed drives without a reboot
>>>:-) I'll definitely investigate the 3ware cards when I need to build a new
>>>RAID server, though.
>>>
>>>
>>But wouldn't a 3ware RAID be slower than an SCSI setup? Unless your
>>current setup is using old SCSI disks. Also how is the load? Lots of
>>simultaneous use or just many quick/small access (ie people using
>>documents/spreadsheets).
>>
>>
>
>There no particular reason for an ATA RAID to be slower than SCSI, assuming
>similar disks in each. 10krpm 'server class' ATA disks are available these
>days, although I don't know that anyone has done a 15krpm one yet.
>
Does SATA have tagged queing? (I don't know offhand if it does...?)
I can guarantee modern SCSI throughput is superior to any of the SATA
drives I've seen to date. Several of the 'hardware sites' (I think
Tomshardware did a writeup on this or anadtech among others) agree with
this statement as well. ATA specs tend to exaggerate their capabilities
even worse than SCSI specs do- burst speeds are all fine and dandy, but
not realistic at all in the real world. Meaning basically in short I
wouldn't choose SATA over SCSI for a production server of any kind where
speed was an issue. ATA has gotten better by far than it was
speed-wise, and I'd be OK with it on a personal workstation for any
purpose, but it's still playing catchup.
>In any case, performance is only one reason to use RAID. My arrays are
>RAID-5's, serving developer home directories over NFS, and a CVS server
>(ie. lots of small file accesses). The main requirements were to have
>some fault tolerance and to get the most out the of disks I could buy with
>the available budget - hence the RAID-5. Read performance is no worse than
>with a single disk, and degrades more gracefully with multiple simultaneous
>access. Write performance is pretty awful, but that's the nature of
>RAID-5. No doubt if I had an unlimited budget I would do things
>differently, but those days are long gone :-(
>
Write performance is awful locally, or over NFS? NFS isn't exactly a
speed demon.
No comment on the unlimited budget as everyone at work just got
(another) 'mandatory pay reduction'...but I do rememeber and miss those,
$^#&*(
;-)
Scott
>I'd also expect/hope that a hardware solution (ATA or SCSI) would be easier
>to manage. Vinum is great, but swapping out a dead drive is still a scary,
>multi-step procedure, that I do infrequently enough that it always requires
>half an hour with the manual and my notes from last time to make sure I get
>it right. With our Windows servers (Compaq Proliants with hardware RAID),
>you just yank the old drive, plug in the new one, and it's done. I'd love
>to be able to do that with the FreeBSD servers as well.
>
> Scott
>
>
>
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