Re: XFS over SSD

[Raz <raziebe@xxxxxxxxx>]

On Mon, Dec 8, 2008 at 4:46 PM, Eric Sandeen <sandeen@xxxxxxxxxxx> wrote:
> Raz wrote:
>> I am thinking of using XFS over a SSD disk.
>> 1. Can I separate xfs meta data ( not just the logging) from the SSD ?
>> can I put the meta on a different disk ?
>
> Are you talking about just the log (see the mkfs man page for external
> logs, as Justin suggested) or all metadata?  For the latter, using the
> realtime subvolume does accomplish this (data on one volume, metadata on
> the other) but that's not used very often.
>
> -Eric
>
I am referring to all the meta data. 128K of erase block for some block map
update is a big penalty. I do not like much rt volumes. I tried that and it is
cumbersome. UBIFS cannot handle 80GB Flash disks ( well, they say it is up to
16GB in MTD web site) . I am about to start benchmarking the SSD with XFS
( versus raw access ) and see how performance degrades, in read and writes.
If there was a way to set XFS meta data ( superblocks, allocation groups...
on a different device) it would have been nice, since we plan to use the SSD
as a fast IO device and data persistence is not the main thing here.

we use XFS on all our SATA based servers, we tweak it ( extents and
raid awareness).
XFS proved to be the fastest file system for appliances that use
Multimedia files
and big IOs ( 1MB).