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Mikhail Teterin
Guest
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 Posted: Mon Jun 04, 2007 4:53 am Post subject: Sharing a 3510 -- NFS vs. QFS? |
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Hello!
We need to share a file-system residing on a StorageTek 3510 device between
multiple servers (3 to 5).
The plan was to make the LUN "native" to one of the server (server0) and
export it to the rest via NFS.
However, it appears, the same LUN can be made "native" to multiple servers
using the QFS solution:
http://www.sun.com/storagetek/management_software/data_management/qfs/
This may help performance (as data will travel to each consumer directly via
fiber, instead of via fiber to the NFS-server, and then via CAT5 to the
NFS-clients).
But is it possible at all? I don't quite understand, how it work -- is 3510
aware of file-system on it? If not, how will take care of the locking and
other attempts by multiple servers to access the same data at the same
time?
Is QFS considered reliable? Is it worth the trouble of learning it for our
case of very few servers?
Can QFS be used to keep two 3510s in sync over LAN (not fiber)?
Thanks for any advice. Yours,
-mi |
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Liam Greenwood
Guest
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| Posted: Mon Jun 04, 2007 9:37 pm Post subject: Re: Sharing a 3510 -- NFS vs. QFS? |
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On Sun, 03 Jun 2007 20:25:42 -0400, Mikhail Teterin
<usenet+meow@aldan.algebra.com> wrote:
| Quote: | Hello!
However, it appears, the same LUN can be made "native" to multiple servers
using the QFS solution:
http://www.sun.com/storagetek/management_software/data_management/qfs/
This may help performance (as data will travel to each consumer directly via
fiber, instead of via fiber to the NFS-server, and then via CAT5 to the
NFS-clients).
But is it possible at all? I don't quite understand, how it work -- is 3510
aware of file-system on it? If not, how will take care of the locking and
other attempts by multiple servers to access the same data at the same
time?
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QFS has to have an ethernet connection between the servers, as well as
them all having fiber access to the disks. One of the serves will be a
metadata server - all file access require a metadata call to the metadata
server over the ethernet, then direct fiber access to the disk.
| Quote: |
Is QFS considered reliable? Is it worth the trouble of learning it for our
case of very few servers?
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As far as I know - it's designed for very large filesystems.
| Quote: |
Can QFS be used to keep two 3510s in sync over LAN (not fiber)?
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I don't believe so.
Cheers, Liam
| Quote: |
Thanks for any advice. Yours,
-mi |
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Mikhail T.
Guest
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| Posted: Mon Jun 04, 2007 11:02 pm Post subject: Re: Sharing a 3510 -- NFS vs. QFS? |
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Liam Greenwood wrote:
| Quote: | QFS has to have an ethernet connection between the servers, as well as
them all having fiber access to the disks. One of the serves will be a
metadata server - all file access require a metadata call to the metadata
server over the ethernet, then direct fiber access to the disk.
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Great, thank you very much -- it now makes sense to me. I now
understand, at least, how it could work in principle -- without the 3510
knowing the details of the filesystem, and concerning itself with just
the device-level workings.
Can you give a guesstimate, on how much space is required on the
metadata server? For example, if the FS is 1.5Tb in size (12 140Gb disks
inside a single 3510), can we use the 100Gb found inside one of the
connected v490 servers for metadata?
| Quote: | Is QFS considered reliable? Is it worth the trouble of learning it for our
case of very few servers?
As far as I know - it's designed for very large filesystems.
Can QFS be used to keep two 3510s in sync over LAN (not fiber)?
I don't believe so.
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Thanks!
-mi |
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Tim Bradshaw
Guest
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| Posted: Mon Jun 04, 2007 11:46 pm Post subject: Re: Sharing a 3510 -- NFS vs. QFS? |
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On 2007-06-04 19:02:09 +0100, "Mikhail T." <mi+usenet@aldan.algebra.com> said:
| Quote: | Can you give a guesstimate, on how much space is required on the
metadata server? For example, if the FS is 1.5Tb in size (12 140Gb
disks inside a single 3510), can we use the 100Gb found inside one of
the connected v490 servers for metadata?
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Wouldn't it be more sensible to use some of the space in the 3510 as
metadata? That would ensure that all the FS data was in one unit at
least (of course, that's a bad thing for redundancy, but I don't think
having the metadata on one set of spindles and the data on another
increases redundancy...) |
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Mikhail Teterin
Guest
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| Posted: Tue Jun 05, 2007 5:46 am Post subject: Re: Sharing a 3510 -- NFS vs. QFS? |
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Tim Bradshaw wrote:
| Quote: | On 2007-06-04 19:02:09 +0100, "Mikhail T." <mi+usenet@aldan.algebra.com
said:
Can you give a guesstimate, on how much space is required on the
metadata server? For example, if the FS is 1.5Tb in size (12 140Gb
disks inside a single 3510), can we use the 100Gb found inside one of
the connected v490 servers for metadata?
Wouldn't it be more sensible to use some of the space in the 3510 as
metadata? That would ensure that all the FS data was in one unit at
least (of course, that's a bad thing for redundancy, but I don't think
having the metadata on one set of spindles and the data on another
increases redundancy...)
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Actually, I'm pretty sure, having the metadata and the data on different
sets of spindles (in different enclosures) does increase redundancy...
Metadata can be rebuilt from the actual data, and the data (or most of it?)
can be recovered using an intact metadata (journal?).
"Metadata separation" is, in fact, listed as one the "Key Features" of QFS:
http://www.sun.com/storagetek/management_software/data_management/qfs/
Besides, each of the v490 servers connected to the 3510 has about 100Gb of
(mirrored) spare capacity anyway :-) The v490s today come with two 140Gb
drives in them, which are mirrored. The OS, optional software, and swap
altogether take only about 40Gb...
Performance should improve too, because the "metadata" server will be
accessing the metadata partition locally, rather than troubling the
external RAID5.
The only question is, will the 100Gb be enough? It ought to be -- we are not
going store 1.5Tb worth of 0-sized files, but getting a word from someone,
who uses QFS already would be most interesting...
-mi |
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Tim Bradshaw
Guest
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| Posted: Tue Jun 05, 2007 11:19 am Post subject: Re: Sharing a 3510 -- NFS vs. QFS? |
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On 2007-06-05 01:46:29 +0100, Mikhail Teterin
<usenet+meow@aldan.algebra.com> said:
| Quote: | Actually, I'm pretty sure, having the metadata and the data on different
sets of spindles (in different enclosures) does increase redundancy...
Metadata can be rebuilt from the actual data, and the data (or most of it?)
can be recovered using an intact metadata (journal?).
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That makes sense, if they can be recovered from each other or, really,
if the metadata can be rebuilt from the data (If you've lost the data
disks having the metadata won't help much I suspect). I'd not found
enough technical info on QFS (is there any available?) to understand
that, though I should have.
| Quote: | Performance should improve too, because the "metadata" server will be
accessing the metadata partition locally, rather than troubling the
external RAID5.
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Well, this depends where the bottleneck is I guess. I can see the
trick QFS is doing - parallel access to data blocks is fine, so long as
someone is in charge of the metadata to ensure thins remain consistent.
And in normal usage (especially for db-type applications) that will
not be a bottleneck - especially if the metadata is a mirror if the
data is raid 5. |
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